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  • 1970-1974  (11,478)
  • Polymer and Materials Science  (10,782)
  • Computational Chemistry and Molecular Modeling  (408)
  • Rat  (288)
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Material
Years
Year
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  • 101
    Electronic Resource
    Electronic Resource
    Masthead (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360131001
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  • 102
    Electronic Resource
    Electronic Resource
    Assignment of the proton nmr chemical shifts of the T—N3H and G—N1H proton resonances in isolated AT and GC Watson-Crick base pairs in double-stranded deoxy oligonucleotides in aqueous solution (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1943-1964 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 300-MHz proton nmr spectra (between 11 and 14 ppm) of a series of double-stranded deoxy oligonucleotides of known sequence have been recorded in H2O solution. These resonances have been assigned to the G—N1H and T—N3H protons of specific base pairs from an evaluation of the temperature dependence of the ring NH linewidths and from the selective ring NH chemical shift changes on actinomycin-D binding. The deoxy oligonucleotides exist predominantly in the DNA-B conformation as evaluated from antibiotic binding studies. Ring-current calculations have been utilized to evaluate the up-field shifts of the G—N1H and T—N3H protons in Watson-Crick base pairs due to the ring currents from the pyrimidine and purine rings of nearest neighbor base pairs in regular DNA-B- and RNA-A-type helices. The perturbations on these up-field ring-current contributions that arise from twisting and tilting a base pair adjacent to the ring NH under study have been evaluated and found to change the calculated chemical shift by ±0.6 ppm for twist and tilt distortions of 〈30°C in a single adjacent base pair. A knowledge of the experimentally assigned ring NH chemical shifts of specific base pairs in known sequences of double-stranded deoxy oligonucleotides coupled with the ring-current tables for the DNA-B helical structure permit the assignment of 13.6 ± 0.1 ppm and 14.6 ± 0.2 ppm for the G—N1H proton of an isolated GC base pair and the T—N3H proton of an isolated AT base pair, respectively.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360131003
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  • 103
    Electronic Resource
    Electronic Resource
    Fluorescence correlation spectroscopy. II. An experimental realization (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 29-61 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the first experimental application of fluorescence correlation spectroscopy, a new method for determining chemical kinetic constants and diffusion coefficients. These quantities are measured by observing the time behaviour of the tiny concentration fluctuations which occur spontaneously in the reaction system even when it is in equilibrium. The equilibrium of the system is not disturbed during the experiment. The diffusion coefficients and chemical rate constants which determine the average time behaviour of these spontaneous fluctuations are the same as those sought by more conventional methods including temperature-jump or other perturbation techniques. The experiment consists essentially in measuring the variation with time of the number of molecules of specified reactants in a defined open volume of solution. The concentration of a reactant is measured by its fluorescence; the sample volume is defined by a focused laser beam which excites the fluorescence. The fluorescent emission fluctuates in proportion with the changes in the number of fluorescent molecules as they diffuse into and out of the sample volume and as they are created or eliminated by the chemical reactions. The number of these reactant molecules must be small to permit detection of the concentration fluctuations. Hence the sample volume is small (10-8 ml) and the concentration of the solutes is low (∼ 10-9 M). We have applied this technique to the study of two prototype systems: the simple example of pure diffusion of a single fluorescent species, rhodamine 6G, and the more interesting but more challenging example of the reaction of macromolecular DNA with the drug ethidium bromide to form a fluorescent complex. The increase of the fluorescence of the ethidium bromide upon formation of the complex permits the observation of the decay of concentration fluctuations via the chemical reaction and consequently the determination of chemical rate constants.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130103
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  • 104
    Electronic Resource
    Electronic Resource
    Circular dichroism studies on the polymerization of N-carboxy α-amino acid anhydride (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 129-138 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The D and L copolymerizations of N-carboxy γ-benzyl glutamate anhydride (NCA) were carried out in a homogeneous solution with various D/L ratios, initiated by either n-butylamine or sodium methoxide, and were followed directly by circular dichroism (CD) to observe the behavior of the secondary structure of growing polymer molecules. In the n-butylamine system, the difference of the helical content between the righthanded and the lefthanded (Δα-helix) gradually increased as the polymerization proceeded, while in the sodium methoxide system, the Δα-helix had a tendency to decrease during the later stages of the polymerization. These results suggest a difference of the power of stereo-selection of monomer antipodes by the growing chain end between these systems, the stereoselectivity by the growing chain end in the sodium methoxide system being higher than that in the n-butylamine system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130108
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  • 105
    Electronic Resource
    Electronic Resource
    The effect of temperature and salt concentration on the circular dichroism exhibited by unionized derivatives of L-alanine in aqueous solution (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 169-183 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism of Ac-Ala-NHMe, cyclo(-Ala-Ala-), Ac-Ala-OMe, Ac-Ala-Ala-OMe, and Ac-Ala-Ala-Ala-OMe has been measured in water and in aqueous salt solutions as a function of temperature. Only cyclo(-Ala-Ala-) exhibits circular dichroism which is independent of temperature. Each of the linear derivatives of L-alanine exhibits a positive circular dichroism in the range 208-218 nm at 15°C in water. Heating reduces the intensity of the positive circular dichroism, and only Ac-Ala-OMe retains positive circular dichroism at 75°C in water. Isothermal addition of salts produces changes in the circular dichroism of linear derivatives of L-alanine which resemble those seen on heating. The relative effectiveness of the salts tested, at a concentration of 4M, is LiCl ≤ KCl = NaCl 〈 MgCl2 ≤ CaCl2 ≤ NaClO4. The circular dichroism of cyclo(-Ala-Ala-) is also affected by the salts. Extrapolation of the results obtained with Ac-Ala-OMe, Ac-Ala-Ala-OMe, and Ac-Ala-Ala-Ala-OMe to a long polypeptide with a -CH2R side chain in the L-configuration leads to the conclusion that this polypeptide should exhibit a temperature-dependent salt-sensitive positive circular dichroism between 208 and 218 nm when it exists as a statstical coil.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130111
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  • 106
    Electronic Resource
    Electronic Resource
    Calorimetric investigation of the helix-coil conversion of polyuridylic acid (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 227-235 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heats of the conformational conversion ΔHc of polyuridylic acid (polyU) in the presence of various cations were determined using a differential scanning microcalorimeter and an isothermal mixing calorimeter. The first method yields a value of ΔHc = 5.2 kcal/mol of base pairs, the second one a value of ΔHc = 6.4 kcal/mol of base pairs. Knowing ΔHc and the maximal slope of the degree of conversion, which was determined from the temperature dependence of the absorbance of polyU solutions at 260 nm, we were able to evaluate the parameter of cooperativity σ. From the relation σ = eΔFstack/RT the stacking free energy ΔFstack could be calculated. Dividing the apparent enthalpy of conversion by the calorimetrically measured enthalpy yields the cooperative length N0 of one helical segment at the midpoint of conversion. The results show that the type of the cation has no influence on the magnitude of ΔHc, whereas the cooperativity of polyU is influenced by the various cations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130116
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  • 107
    Electronic Resource
    Electronic Resource
    In memoriam: E. Scoffone (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 861-862 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130502
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  • 108
    Electronic Resource
    Electronic Resource
    Dynamic light scattering studies of poly-L-lysine HBr in the presence of added salt (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 903-908 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Clipped autocorrelation functions for the fluctuating intensity of light scattered from dilute solutions of poly-L-lysine in 0.2 M NaBr have been observed over a wide range of time scales down to 1.83 μsec, and over a wide range of pH. Two poly-L-lysine samples of molecular weight 35,000 and 200,000, respectively, were compared to determine the extent of draining of the so-called random-coil configuration. The observed correlation functions were in general very satisfactorily represented by simple translation diffusion of single molecules. At high pH ∼10-10.4, there was evidence of considerable aggregation, but no indication whatsoever of any unusually fast component, as reported recently by Jamieson et al. for poly-L-lysine HBr in the absence of salt.A 30% rise in the diffusion coefficient to a peak at pH 10 parallels the previously reported dip in the intrinsic viscosity, and is interpreted in terms of a more compact structure in that pH region between the coil and helix extremes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130506
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  • 109
    Electronic Resource
    Electronic Resource
    Studies of deoxyribonucleoproteins progressively depleted of proteins in solutions of various ionic strengths (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 863-877 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformation of deoxyribonucleoprotein (DNP) from calf thymus at different stages of deproteinization was studied.The dissociation of the first portion of histone produces no effect on the hydrodynamical and optical behavior of DNP particles. The conformational transition of a macromolecule was observed as soon as the ratio of protein to DNA ≤ 0.9.The effect of ionic strength on the conformation of DNP particles with high protein content was more strongly pronounced than that for DNA. On the contrary, DNP particles depleted of proteins (protein/DNA 〈 0.9) were found to be less sensitive than DNA to the variation of ionic strength. These data imply that the DNP molecules rich in proteins possess a superstructure that is destroyed as the protein/DNA ratio becomes 0.9.The data were analyzed in view of current theories on various model concepts. The most probable model to describe the DNP molecule was chosen by comparing the calculated and experimentally obtained parameters. We believe that DNP is best described as a “compressed coil,” possibly including superhelical regions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130503
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  • 110
    Electronic Resource
    Electronic Resource
    Synthesis of some amino acids, sugars, and peptides in cold plasma abiotic synthesis of some high-molecular-weight proteid-like structures (V) (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 943-954 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of some high-molecular-weight protenoid structures in radiofrequency cold plasma conditions are discussed. The fractionation results of the raw product and the spectrum of free and protenoid-bound amino acids are given. The uv analysis of these compounds is presented.A protein-forming mechanism that might have existed on the primitive earth is proposed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130510
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  • 111
    Electronic Resource
    Electronic Resource
    An electron microscopic method for studying nucleic acid-protein complexes. Visualization of RNA polymerase bound to the DNA of bacteriophages T7 and T3Dedicated to the memory of Dr. Jean-Pierre Tranzer. (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 995-1009 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Double-stranded DNA can be readily adsorbed on mica or directly on carbon coated grids from the surface of solutions containing ethidium bromide, actinomine, or propidium diiodide. The DNA molecules are unfolded, well separated, and show a length distribution similar to molecules prepared by protein monolayer techniques.Since the intercalating dyes tested do not lead to an increased apparent diameter of the nucleic acid the method is useful for the study of nucleic acid-protein complexes. As a model, the binding of E. coli RNA polymerase to phage T7 and T3 DNA was examined under different conditions. The enzyme can easily be identified and its position along the DNA molecule can be mapped.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130514
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  • 112
    Electronic Resource
    Electronic Resource
    Sequential oligopeptides. Synthesis and characterization of the oligopeptides and a polypeptide with the repeating sequence L-norvalyl-glycyl-L-proline (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1055-1066 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of a series of oligopeptides (from the tripeptide to the octadecapeptide) with the repeating sequence L-norvalyl-glycyl-L-proline and a polytripeptide with this sequence are reported. The oligomers were synthesized step by step using the mixed anhydride method. All the products were chemically and optically pure. The polymer was prepared by the active ester method, using the p-nitrophenyl ester as the polymerizable tripeptide derivative. Good yield of relatively high average molecular-weight polymer was obtained. In the accompanying paper conformational investigations, both in solution and in the solid state, on the oligomers and the polymer are described.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130518
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  • 113
    Electronic Resource
    Electronic Resource
    Synthesis and conformational study of poly(Nδ-carbobenzoxy, Nδ-benzyl-L-ornithine) and poly(Nδ-benzyl-L-ornithine) (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1117-1125 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(Nδ-carbobenzoxy, Nδ-benzyl-L-ornithine) (PCBLO) was prepared by the standard NCA method. PCBLO was converted into poly(Nδ-benzyl-L-ornithine) (PBLO) through decarbobenzoxylation with hydrogen bromide. The monomer Nδ-benzyl-L-ornithine was synthesized by reacting L-ornithine with benzaldehyde, followed by hydrogenation. The conformation of the two polypeptides was studied by optical rotatory dispersion and circular dichroism. PCBLO forms a right-handed helix in helix-promoting solvents. In mixed solvents of chloroform and dichloroacetic acid (DCA) it undergoes a sharp helix-coil transition at 12% (v/v) DCA at 25°C, as compared with 36% for poly(Nδ-carbobenzoxy-L-ornithine) (PCLO). Like PCLO, the helix-coil transition is “inverse,” that is, high temperature favors the helical form. PBLO is soluble in water at pH below 7 and has a “coiled” conformation. In 88% (v/v) 1-propanol above pH (apparent) 9.6 it is completely helical. In 50% 1-propanol the transition pH (apparent) is about 7.4; this compares with a pHtr of about 10 for poly-L-ornithine in the same solvent.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130605
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  • 114
    Electronic Resource
    Electronic Resource
    Interaction of ethidium bromide with DNA. Optical and electrooptical study (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1141-1160 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of ethidium bromide to DNA has been studied by various optical methods. From fluorescence polarization studies, and film, electric linear dichroism, and circular dichroism spectra, we propose assignments of the absorption bands of the dye, which are discussed in connection with wave-mechanical calculations recently reported.The optical activity induced in the dye absorption bands upon binding to DNA was attributed to various origins depending on the electronic transition considered. The visible absorption band displayed a circular dichroism due to the asymmetry of the binding site and independent of the amount of binding. The transition identified at 378 nm from the circular dichroism and electric dichroism observations was thought to be due to a magnetic-dipole transition. It remained constant with increasing amounts of dye bound. The main ultraviolet band showed circular dichroism characteristics corresponding to exciton interactions between dye molecules bound to neighboring sites.The electric dichroism observed for the strongly bound dye molecules indicated that the phenanthridinium ring of ethidium bromide was probably not perfectly parallel to the DNA base planes. When the amount of dye bound to DNA exceeded the maximum amount compatible with the exclusion of adjacent binding sites, the electric dichroism decreased owing to the appearance of externally bound dye molecules with no contribution to the dichroism.Sonicated DNA was used to study the lengthening of the DNA molecule upon complexation. Although the viscosity of the complexes increased with the amount of binding, the rotational diffusion coefficient measured by the electric birefringence relaxation was not detectably affected. The absence of variation in the electric birefringence with the binding indicated that the DNA base stacking remained unaltered.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130607
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  • 115
    Electronic Resource
    Electronic Resource
    Polymerization of optical isomers of phenylalanine N-carboxyanhydride by poly (N-methylalanine) diethylamide (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1205-1212 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the polymerization of phenylalanine N-carboxyanhydride (NCA) using poly(N-methyl-L-or DL-alanine) diethylamide as initiator, the polymerization rate was L-NCA ≃ D-NCA 〉 DL-NCA. This is a new type of selective polymerization and indicates the incompleteness of earlier investigations to study the asymmetrically selective polymerization without D-NCA. Neither secondary structure nor optical activity of the polymeric initiator is a reason for the selectivity. Hence the cause for the selectivity was sought in the properties of the NCA's in solution. However, the selectivity was not observed in the polymerization initiated by poly(L-phenylalanine) dimethylamide. The importance of the initiator being a secondary amine type was suggested. The experimental results are discussed on the basis of these considerations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130612
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  • 116
    Electronic Resource
    Electronic Resource
    Conformational stability in dinucleoside phosphate crystals. Semiempirical potential energy calculations for uridylyl-3′-5′-adenosine monophosphate (UpA) and guanylyl-3′,5′-cytidine monophosphate (GpC) (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1243-1259 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Classical potential energy calculations were performed for the dinucleoside phosphates UpA and GpC. Two widely accessible low-energy regions of conformation space were found for the ω′, ω pair. That of lowest energy contains conformations similar to helical RNA, with ω′ and ω in the vicinity of 300° and 280°, respectively. All five experimental observations of crystalline GpC, two of ApU, and the helical fragment of ApApA fall in this range. The second lowest region has ω′ and ω at about 20° and 80°, respectively, which is in the general region of one experimentally observed crystalline conformer of UpA, and the nonhelical region of ApApA.It is concluded that GpC and ApU, which were crystallized as either sodium or calcium salts, are shielded from each other in the crystal by the water of hydration and are therefore free to adopt their predicted in vacuo minimum energy helical conformations. By contrast, crystalline UpA had only 1/2 water per molecule, and was forced into higher energy conformations in order to maximize intermolecular hydrogen bonding.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130615
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  • 117
    Electronic Resource
    Electronic Resource
    Structure of aggregates and helix-coil transition of polypeptides by dielectric measurements. I. Poly-γ-benzyl-L-glutamate in dioxane and dioxane-dichloroacetic acid (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1293-1308 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dielectric dispersion measurements on poly-γ-benzyl-L-glutamate (PBLG) in dioxane and dioxane-dichloroacetic acid (DCA) mixtures in the frequency range 200 Hz-2 MHz were made in order to study the structure of molecular aggregates. The structure of aggregates is explained on the basis of the variation of dipole moment and relaxation time with degree of aggregation. PBLG was found to form linear head-to-tail-type aggregates in dioxane. These aggregates gradually reduce in size without loosing their α-helical structure during the process of disaggregation obtained by either adding DCA to the solution in dioxane or by heating. It was confirmed that the addition of 30 wt % DCA completely destroys the aggregation of PBLG in dioxane at 30°C. Thermal disaggregation, however, was not complete even at a temperature approaching the boiling point of the solvent.A reaction scheme for aggregation is proposed and equilibrium constants are calculated at various stages of aggregation. The enthalpy of aggregate formation is found to be -3 kcal/mol. Results of optical rotatory dispersion measurements of the helix-coil transition in this system are also presented.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130702
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  • 118
    Electronic Resource
    Electronic Resource
    Solution properties of synthetic polypeptides. XVII. Stability of the α-helical conformation of poly(γ-benzyl L-glutamate) in helicogenic solvents (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1347-1356 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Zimm-Bragg parameters s and σ were determined for poly(γ-benzyl L-glutamate) (PBLG) in m-cresol and in dimethylformamide (DMF) from ORD data as a function of molecular weight. It was found that, within the temperature range between 10 and 55°C and on the average, s = 1.61 ± 0.1 and √σ = 0.04 ± 0.01 in m-cresol and s = 1.65 ± 0.05 and √σ = 0.045 ± 0.015 in DMF. The values of s in m-cresol decreased with increasing temperature, while the values of σ in the same solvent increased. This result for s suggests that PBLG in m-cresol will undergo a thermal helix-coil transition of normal type. The parameters in DMF showed no appreciable trend to vary with temperature. Aside from the difference between the two solvents, our results are consistent with existing data for various conformation-dependent properties such as light-scattering radius, intrinsic viscosity, and dipole moment, each indicating that the polypeptide chain has some flexibility in helicogenic solvents.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1974.360130706
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  • 119
    Electronic Resource
    Electronic Resource
    Calculations of the circular dichroism of double-helical nucleic acids. II. Effects involving n → π* transitions (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1391-1403 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism of double-helical nucleic acids was calculated as a function of geometry, including terms involving n → π* transitions. The “nonbonding” n or σ orbitals were of the azine type, delocalized, but concentrated at the nitrogen atoms of the purines and pyrimidines. Dynamic coupling of the magnetic moments of the n → π* transitions with the electric moments of π → π* transitions generated important terms. Mixing of electric dipole character into n → π* transitions by the static electric field perturbation of the molecule is of lesser importance. The largest contributions of n → π* transitions to the circular dichroism of double-helical nucleic acids are comparable in magnitude to the sum of π → π* terms only for geometries where the circular dichroism is weak. Using both n → π* and π → π* contributions one is able to match experimental and calculated circular dichroism spectra for DNA's over a much wider range of conditions than was possible previously.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130710
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  • 120
    Electronic Resource
    Electronic Resource
    Raman spectral changes induced by side-chain interactions in racemic poly-γ-benzyl glutamate (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1435-1445 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser Raman spectra are reported for solid films cast from a series of solutions containing mixtures of right- and left-handed α-helices of poly-γ-benzyl-L- and D-glutamate. Procedures were established for producing spectra that were reproducible in position to ±0.3 cm-1 and in relative intensity to a few percent for features of interest. Spectra for the pure L and pure D polymers were identical, as expected. Several small but definite spectral changes appear in the mixtures, reaching a maximum for the racemic 50:50 mixture. The changes are a shift of -1.4 cm-1 in the amide I peak at 1650.5 cm-1; a shift of about -5 cm-1 in the partially resolved amide III peak at 1291 cm-1; a shift of +2.5 cm-1 in the benzyl peak at 3062.5 cm-1; changes in relative intensity of as much as 50% in several regions; and the marked enhancement of several peaks, particularly that at 254 cm-1. These changes are discussed in terms of side-chain interactions in the packing of right- and left-handed helices.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130714
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  • 121
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    Study of the self-diffusion coefficients of cations in the presence of an acidic polysaccharide (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1535-1548 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Self-diffusion coefficient measurements have been applied to the study of Na+, Ca++, and Sr++ in the presence of a linear acidic polysaccharide extracted from cartilage, i.e., chondroitin sulfate. A series of experimental determinations was made with and without supporting electrolytes, and an analysis of experiments involving the separation of the electrostatic interaction terms by an extension of Manning's theory produced results showing the preponderant nature of these electrostatic terms. The specificity of each type of ion or the influence of the pH can be considered merely as higher order corrections with respect to the preceding interactions. Counterion concentration ranges and pH ranges were determined, where either the alkaline-earth counterions become free and hence move with their normal diffusion rate, or these cations are associated with the polyelectrolyte molecule, thus giving a diffusion coefficient similar to that of the macromolecule, or the apparent diffusion coefficients vary between these two extreme diffusion rates as a function of the association equilibria. This variation can be expressed as a function of the linear charge density parameter ξ related to the structure of the polyelectrolyte, the value of which was determined and found in good agreement with published values.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130803
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  • 122
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    The calculated circular dichroism of polyproline ii in the polarizability approximation (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1635-1651 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism (CD) spectrum of polyproline II (PPII) has heretofore been moderately well calculated from exciton theory only at the expense of assuming unreasonable chain conformations and accepting a conservative spectrum in the 180-250-nm region (which is not observed). We have incorporated far uv transitions in the polarizability approximation and, together with the π2π* transition, have calculated the resulting correction to the exciton model. This has been accompanied by a modified assignment of the ππ* transition in PPII, and a simultaneous calculation of the absorption and CD spectra of the α-helix, β structure, PPI, and PPII. We obtain good agreement with the observed CD spectrum of PPII in the 180-250-nm region for acceptable chain conformations. In addition, we predict a negative CD into the far uv, in agreement with recent experimental observations. Our calculations also reproduce features of the far uv CD spectrum of the α-helix, and are in agreement with the CD spectra of the β chain and PPI. The calculated CD of the unordered polypeptide chain is not significantly influenced by far uv contributions, indicating that our previous calculation is valid for such a system. These results demonstrate the importance of incorporating far uv transitions in order to achieve an adequate theoretical explanation of the CD spectra of polypeptides.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130810
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  • 123
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    Masthead (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130901
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  • 124
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    Hydrodynamic properties of a new plasma expander: Polyhydroxyethylaspartamide (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1721-1729 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intrinsic viscosity and molecular weight of several samples of polyhydroxyethylaspartamide with differing degrees of polymerization were determined and related, according to the Mark-Howink equation. The a exponent is consistent with a random-coil structure. The average unperturbed dimensions of the polymer, the dimensions in water, and the water-polymer interaction parameter were calculated according to Flory and Fox. The interaction of the polymer with water may explain its good efficacy as a plasma expander, as has previously been demonstrated in biological experiments. The behavior of the molecule in 6 M guanidine hydrochloride solution was also studied: this solvent has a very slight effect on the configuration of the polymer, in contrast with its normal effect on proteins.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130904
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  • 125
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    Microcalorimetric investigation of dilute and concentrated solutions and films of the polydeoxynucleotide poly[d(A-T)·d(A-T)] (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1751-1756 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Microcalorimetric heat capacity measurements on dilute and concentrated solutions and films of poly[d(A-T)·d(A-T)] in 2 M sodium chloride have been carried out. Values for enthalpy, entropy, and temperature of the helix-coil transition have been found to depend on the polymer concentration, and to have maxima near 20% (w/w) of polymer. The results are discussed in terms of polynucleotide hydration as one of the structure stabilizing factors.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130908
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  • 126
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    Evaluation of kinetic parameters of thermal decomposition of native collagen by thermogravimetric analysis (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1791-1807 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetic parameters associated with the thermal decomposition of native collagen have been obtained by thermogravimetric techniques. In order to achieve this a thermogravimetric analysis was carried out in the temperature range of 25°C to about 1000°C. In this temperature range, it had been found that the differential primary weight loss curve had yielded three distinct peaks for the tendon collagen. The thermal decomposition corresponding to each peak was analyzed to retrieve its kinetic parameters. The peak temperature associated with the first peak decreased as the water content in a sample increased, while that of the second peak was independent of its hydration condition. It is believed that the first and the second peaks are, respectively, results of: (1) dissociation of water from collagen, and (2) of breaking of the collagen molecule itself. The third peak has not been easily identified so far. The activation energy and the order of water decomposition are obtained by various known methods. The results obtained by these different approaches agree reasonably well. The kinetic parameters of second and third peak are also obtained and reported here.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130912
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  • 127
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    Recursion relation generation of probability profiles for specific-sequence macromolecules with long-range correlations (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1859-1871 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of calculating detailed probability profiles giving the probability of each unit in the chain to be in the ordered state (and all other average quantities as well including the fraction of strand association) for specific-sequence macromolecules requiring statistical weights that correlate up to the total number of units in the chain (e.g., DNA, collagen) is formulated in terms of recursion relations for appropriate a priori and conditional probabilities, thus generalizing the approach of Lacombe and Simha for nearest-neighbor correlations in specific sequence macromolecules. The technique allows the probability profiles for chains of thousands of units to be calculated in minutes making no approximation in the basic model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130916
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  • 128
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    Studies on poly(L-lysine50, L-tyrosine50)-DNA interaction (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1909-1926 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interaction between poly(Lys50, Tyr50) and DNA has been studied by absorption, circular dichroism (CD), and fluorescence spectroscopy and thermal denaturation in 0.001M Tris, pH 6.8. The binding of this copolypeptide to DNA results in an absorbance enhancement and fluorescence quenching on tyrosine. There is also an increase in the tyrosine CD at 230 nm. The CD of DNA above 250 nm is slightly shifted to the longer wavelength which is qualitatively similar to, but quantitatively much smaller than, that induced by polylysine binding. At physiological pH the poly(Lys50, Tyr50)-DNA complex is soluble until there is one lysine and one tyrosine per nucleotide in the complex. The same ratio of amino acid residues to nucleotide has also been observed in copolypeptide-bound regions of the complex. The addition of more poly(Lys50, Tyr50) to DNA yields a constant melting temperature, Tm′, for bound base pairs at 90°C which is close to that of polylysine-bound DNA under the same condition. The melting temperature, Tm, of free base pairs at about 60°C on the other hand, is increased by 10°C as more copolypeptide is bound to DNA. As the temperature is raised, both absorption and CD spectra of the complexes with high coverage are changed, suggesting structural alteration, perhaps deprotonation, on bound tyrosine. The results in this report also suggest that intercalation of tyrosine in DNA is unlikely to be the mode of binding.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360130919
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  • 129
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    Normal vibrations of cyclic tetraglycine (1974)
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 2565-2570 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Normal vibration analysis of cyclic tetraglycine has been carried out employing the Urey-Bradley force field and the vibrational assignments are compared with those in related molecules.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1974.360131213
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  • 130
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    Announcement (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 315-316 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080216
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  • 131
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    Irreducible tensor operator methods in intermediate-field coupling (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 347-362 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The algebra of irreducible tensor operators is developed in the intermediate-field coupling case. The Wigner-Eckart theorem is formulated for a simple irreducible tensor operator as well as for the Kronecker and scalar products of these operators. The expressions required for the calculation of Coulomb repulsion, crystal field splitting, spin-orbit interaction, and Zeeman effect are given in detail. Recent applications to various problems in spectroscopy and magnetism of transition metal compounds are referred to.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080304
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  • 132
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    SCF equations for pure spin states with many-particle interactions (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 539-546 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: SCF equations for any pure spin state are given for a spin-free system with many-particle interactions. The equations are very simple and explicit. Due to the use of different antisymmetric requirement our equations are different from some of the other methods. In our method, the abstract group theory formalism is converted into some explicit and straightforward equations which makes the many-particle interaction problem easier to handle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080405
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  • 133
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    Unified treatment of two-electron integrals. II. One-center, electron repulsion, spin-spin and spin-orbit integrals containing rij (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 635-642 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: General formulas are obtained for evaluating a basic type of one-center two-electron integral which arises in the computation of expectation values of spin-spin and spin-orbit operators over explicitly correlated wave functions. The correlation terms are assumed to be in the form of products of Slater functions and powers (not necessarily integer) of the interelectronic coordinate rij.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080502
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  • 134
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    Perturbative ab initio calculations of intermolecular energies. II. The He ··· He problem (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 17-28 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ground state energy of the He2 system is calculated according to the techniques described in Paper I around the van der Waals equilibrium, without assuming the constancy of the intraatomic correlation energies. The second-order results do not present an attractive region; the S2 decrease of the intraatomic correlation correlation corrections is larger than the attractive interatomic correlation corrections. The further orders reverse progressively the situation and finally give a qualitatively correct potential curve after the fifth order. Reaching almost exact solutions in the considered basis, one can demonstrate that the intermolecular calculation of the system A + B in the union of the basis for A and B involves an energy decrease which simply represents the effect of the extension of the basis set; and that a proper intermolecular calculation must compare the A + B energy with the A and B energies calculated in conveniently extended basis sets including the vacant MO's of the partner.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080103
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  • 135
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    More on molecular electronic structure of metal phthalocyanines (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 79-82 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular orbitals of some of the 3d-transition metal phthalocyanines have been calculated. π-Electron charge densities over the atomic sites and the optical properties of the metal phthalocyanines have been calculated. The effect of the introduction of different metal atoms in the centre of the organic ring on the physical properties of the metal phthalocyanines has been discussed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080108
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  • 136
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    Convergence problems in the solution of SCF equations (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 107-117 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some problems connected with the convergence of iterative solutions of the Hartree-Fock equations for the open shell systems are discussed. The nonuniqueness of the Hartree-Fock operator form is used.The method of iterating by the operator's power is developed for obtaining solutions of the Hartree-Fock equations. Some particular results for the molecules Li2+, Li2- are presented.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080112
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  • 137
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    Masthead (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080201
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  • 138
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    Correlation effects in the low-lying excited states of the PPP models of alternant hydrocarbons. I. Qualitative rules for the effect of limited configuration interaction (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 951-970 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simple rules for an estimate of the correlation effects in the low-lying states of alternant hydrocarbons, as described by the Pariser-Parr-Pople Hamiltonian, are formulated. These rules are based on the alternancy and spin symmetry classification of states in both strongly and weakly correlated limits and on the valence bond characteristics of those states in the fully correlated limit. It is shown that the largest effect of the electron correlation will be found for the singlet “minus” states (using Pariser's classification of the alternancy symmetry species), a smaller effect for the triplet “plus” states, and a much smaller effect for the remaining states. These rules are exemplified by limited CI calculations including all monoexcited and all mono- and bi-excited configurations, respectively, for a number of π-electronic systems. In view of these rules the success of the PPP model in the monoexcited CI approximation may be understood.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080610
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  • 139
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    Potential energy integrals in semiempirical MO methods (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 263-266 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two-center core-electron attraction integral VAB in zero-differential overlap semiempirical MO methods is examined. It is concluded that core-valence orthogonality and valence symmetrical orthogonalization effects must be considered, and that these effects provide justification for the CNDO/2 approximation VAB = ZBγAB.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080213
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  • 140
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    Static and dynamic first- and second-order properties by variational wave functions (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 293-314 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of the evaluation of first- and second-order energies by the use of arbitrary variational wave functions is examined in detail for time-independent perturbations as well as for time-dependent perturbations. By using a compact formalism the general formulae to be used for the case of a fully optimized set of variational parameters are readily obtained and the most prominent features are examined. The generality of the approach is tested by showing how some widely used methods are obtained by using particular types of variational wave functions. The case of incompletely optimized sets of variational parameters is examined examined extensively and several approaches at different levels of approximation are proposed. Emphasis is put upon the importance of considering, in the calculation of higher-order energies, the variational parameters which may be of negligible importance, and thus often neglected, in the absence of perturbations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080215
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  • 141
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    Spin projected EHF method: Calculations for a four-electron model system (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 363-372 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spin projected extended Hartree-Fock equations for successive optimization of the orbitals are derived for the four-electron case and applied to butadiene in the PPP approximation. The method shows an excellent convergence and gives 91.4% of the correlation energy for the given model-Hamiltonian.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080305
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  • 142
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    Molecules-in-molecules calculations with fixed resonance integrals (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 427-433 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple equation for the evaluation of resonance integrals from overlap integrals and ionization potentials of the molecular fragments is suggested for molecules-in-molecules π electron calculations. The singlet π → π* transition energies of some benzene derivatives containing donor substituents were calculated. The best results were obtained if in the expression of the resonance integral the first experimental ionization potential of the methyl derivative of the donor groups is used.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080309
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  • 143
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    Approximate valence-shell electron unrestricted Hartree-Fock calculations with orthogonalized atomic orbitals: Proton hyperfine splittings in benzyl and related radicalsPaper presented at the First International Congress of Quantum Chemistry, Menton, France, July 4-10, 1973. (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 451-465 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified INDO procedure has been used to calculate the proton hyperfine splittings in benzyl and the isoelectronic anilino, phenoxy and 2-azabenzyl as well as 2- and 3-thenyl radicals. The present procedure differentiates between s-, p- and d-orbitals on an atom in estimating various integrals involving them, satisfies the rotational invariance requirements and employs an orthogonalized basis set of atomic orbitals for obtaining core-Hamiltonian matrix elements. The calculations based on using the exponents which depend only on the type of orbital and the nature of atom fail to provide correct relative order of ortho and para proton splittings in benzyl as well as anilino, phenoxy and 2-azabenzyl radicals. On the other hand, use of the exponents which are modified according to the charge densities in various orbitals leads to a high absolute value for para proton splitting compared to that for ortho proton splitting which in case of all these radicals is in agreement with experiment. A spin density calculation on benzyl, anilino and phenoxy radicals considering the variation of one-center one-electron and one-center two-electron integrals for different protons with their charges is found to yield further improvement in the relative order of ortho and para proton splittings in all these radicals. In 2- and 3-thenyl radicals the role of 3d-orbitals on sulfur has also been examined. To our knowledge, no unrestricted INDO calculations including 3d-orbitals on sulfur have been reported in the literature so far.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080311
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  • 144
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    The loge theory as a starting point for variational calculations. I. General formalismPresented at the 7th Meeting of the International Academy of Molecular Science, July 1973. (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 499-522 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that any expectation value of any observable associated with a molecule is the sum of loge contributions and of loge pair contributions. This result provides a rigorous theoretical basis for the study of additive properties of molecules.It is demonstrated that molecular wave functions (exact or approximate) can be expressed as a sum of functions corresponding to the various electronic events. Furthermore any of these event functions can be expressed in terms of correlated loge functions. This expression suggests many kinds of variational procedures of calculating wave functions (known methods and new ones).The case in which noncorrelated completely localized loge functions are used is discussed. If continuous functions are used the variational equation reduces to a sum of independent variational equations, each one corresponding to a particular electronic event. This is not so when discontinuous functions are used or when a delocalized function is added to replace the correlation interloge function.The noncorrelated completely localized loge model is analyzed in more detail. It is seen that local spin operators can be introduced and that each event density operator is the product of the loge density operators. Therefore that model is an independent loge model. The corresponding generalized self-consistent field equations are derived. This treatment helps us to understand how a localized state of a molecule can produce an ion containing a delocalized region, a phenomenon which is sometimes at the origin of some misunderstanding in photoelectron spectroscopy. Finally it is seen how virtual loge functions can be introduced to describe excited states.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080403
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  • 145
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    Matrix elements in configuration interaction calculations (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 605-617 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is proposed for the calculation of matrix elements among various states of atoms. A set of tensor operators is the only entity in the formalism, and all formulas involve merely the vacuum expectation values of these tensor operators and the recoupling transformation coefficients. Some numerical examples are given for the Coulomb interaction matrix elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080410
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  • 146
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    Hybridization by the maximum overlap methodSupported in part by the National Science Foundation (Grant GP-31373 and 14012X). (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 643-676 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A brief survey of the maximum overlap method is presented and some computational aspects of the approach are discussed. The hybrid compositions and bond overlaps are reported for some thirty small ring compounds and a list of characteristic hybrids for various structural environments is given. The table of characteristic hybrids is extended to acyclic hydrocarbons and the transferability of the maximum overlap hybrids is demonstrated. Those aspects of the method which depend on geometrical properties of molecules have been considered in some details and the discussion is extended to some structural features of cyclic systems. In particular the asymmetry of bonds of spiro carbon atom is examined and rationalization of puckering of large macrocyclic systems is presented. In the summary it is pointed to the method and its potential to discuss structural aspects of molecules at the particular level of accuracy expected to be of great use in organic and physical organic chemistry. Further development and improvement of the method is mentioned, but already in the present form it can produce hybrids which may constitute a useful basis for other more ambitious semiempirical calculations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080503
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  • 147
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    Eigenspace manipulation in SCF theory: General formalism (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 423-426 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general formalism in order to deal with SCF eigenspace manipulation is developed. It can be shown that the initial generalized secular equation splits into a set of secular equations, each of which in turn can modify independently any predetermined subset of the SCF manifold.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080308
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  • 148
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    An improved Hellmann-type pseudopotential for atoms and molecules (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 435-450 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concept of pseudopotentials offers much attractiveness for the quantum mechanical evaluation of the physical properties of atoms and molecules. The ideas of Hellmann, in which the repulsive and fermion character of inner electrons can be mimicked by an experimentally fitted, exponentially damped potential term, are especially attractive. Unfortunately, it is found that such a simple expression can only be used in a very limited number of cases, such as for the alkali metals, and even then fails for the simple case of lithium.The present study shows that the Hellmann idea can readily be extended by including a second “shielded potential” term evaluated from tabulated previous Hartree-Fock calculations. The new expression for the model pseudopotential is both simple and effective. With it, the inner potential of any of the alkali metal atoms, including lithium, can be represented so that calculation of the molecular properties of the metal dimers can be accomplished. Calculations for Li2, Na2, and K2 show the binding energies and equilibrium interatomic distances to be quite well given, in agreement with both chemical experience and spectroscopic evidence.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080310
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  • 149
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    An investigation into the use of expansion methods in the calculation of chemical shifts and diamagnetic susceptibilities (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 745-754 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chemical shift and the diamagnetic susceptibility of the hydrogenic atom with magnetic dipole and origin of the external magnetic field vector potential noncoincident with the hydrogenic nucleus have been calculated from perturbation theory using a set of expansion functions whose radial parts are single exponent associated Laguerre functions. In contrast to hydrogenic expansion functions these functions give rapid convergence to the exact values of the second-order energy summations when centred at the hydrogenic nucleus. The rate of convergence is fairly insensitive to the choice of expansion function exponent.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080509
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  • 150
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    Calculation of the magneto-optical activity of the hydrogen moleculeResearch supported by the National Science Foundation and the Danish Science Foundation. (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 789-797 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We calculated the Verdet constant of the hydrogen molecule. We found that the angle of rotation may be represented by φ0 = A0Hv2/(v02 - v2)2 where A0 is 3.23 × 10-33 microminutes sec2 per oersted-cm-atmosphere. This is in agreement with the experimental observations where φ0 is given by the same frequency dependence with the constant A0 × 2.72 = 10-33 in terms of the same units.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080514
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  • 151
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    Spin-Projected extended Hartree-Fock equations. II. Odd-electron systems (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 893-899 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spin-projected extended Hartree-Fock equations discussed in Part I for an even number of electrons are given here for the odd-electron case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080605
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  • 152
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    Matrix elements in all valence electron models (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 925-940 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Model Hamiltonians for all valence electron calculations are examined with regard to the possibility of obtaining consistent sets of matrix elements for the description of electromagnetic processes such as photon absorption, optical activity, and magneto-optical activity. Linear and angular momentum and position operator matrix elements are related to Hamiltonian matrix elements through symmetry relations and equations of motions. The possibility of elimination of empirical interatomic matrix elements is studied.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080608
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  • 153
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    Symmetry in the Heitler-London method. I. The connection of the molecular point group with its electron permutation group in the Heitler-London method (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 163-169 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The connection between the electron coordinates permutation group and the molecular point group is exhibited in the framework of the Heitler-London method. It is shown that the initial wave function of a molecule in the Heitler-London method can be written in such a form, that the effect of the point group operations upon this function corresponds to the permutation of the sets of electron coordinates of the ions and the subsequent multiplication of this function by some constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080203
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  • 154
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    Integral transform functions and separable potentials (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 209-221 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: General forms for asymptotic wave functions are derived from properties of the relevant Green's function. The use of separable potentials constructed from the asymptotic functions is described and the relation with integral transform functions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080208
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  • 155
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    A comparative calculation on excited state energies of some conjugated hydrocarbons (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 247-253 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The energies of the single-configuration lowest π - π* singlet and triplet states of some conjugated hydrocarbons have been calculated by the MC-SCF method using the conjugate-gradient technique of minimisation. The results are compared with those calculated by other methods currently in use, like (a) single-configuration calculation with VN-1 potential for virtual orbitals; (b) CI calculation involving singly excited states; and (c) TDHF method. It has been concluded that the results for the MC-SCF method are very good, considering that only a single open-shell configuration is involved.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080211
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  • 156
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    Masthead (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080301
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  • 157
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    Validity of the three-center, four-electron model for stability of rare gas halides on the basis of exchange perturbation theory (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 335-345 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a previous publication [1] we analyzed the stability of rare gas halides on the basis of exchange perturbation theory of the Rayleigh-Schrödinger type, using a three-center, four-electron model. In this paper, the analysis is extended to a (n + 1)-center, (n + 2)-electron model for rare gas halides of composition RXn, where R is the rare gas atom and X the halogen atom, in order to investigate the validity of the three-center, four-electron model. The compounds analyzed are XeFn, XeCln, KrFn and KrCln with n = 3 and 4, in different geometric configurations and for different states of total spin S. As before, we use exchange perturbation theory in first and second orders. The results are in good agreement with those obtained in the previous analysis and with experiments. Specifically, it is found that chlorides of rare gas atoms are not stable, that XeF4 has the square-planar configuration and that trifluorides cannot exist. The possible existence of KrF4 is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080303
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  • 158
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    Generalized open shell SCF theory (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 373-394 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A generalized form of the coupling operator technique in SCF theory has been developed. In the formalism presented here, the monoconfigurational problem may be treated as a particular case of the multiconfigurational framework. The matrix form of the operators has been analyzed; in the LCAO context a structure has been found which is very adequate for computational purposes.Some examples are also presented which show the usefulness of the theory, emphasising the CNDO and INDO approximations. Within the application of the method to ab initio calculations, some He and second row atoms states have been studied. The He first excited singlet is also studied, the result of the analysis of such a problem being that the nonorthogonality between the singlet functions of the fundamental and of the first excited states play a primordial role in the efficiency of the method.In no case have the calculation problems, appearing in the application of the theory, been of a more difficult nature than those normally found in the application of the formalism for closed shells.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080306
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  • 159
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    Interaction of two H2 molecules: Comparative study of various perturbation procedures (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 467-489 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variational calculation of the interaction between two H2 molecules using minimal basis set of 1s functions is performed to check the efficiency of various versions of the perturbation theory for intermolecular interactions. The matrix procedure starting with the zero-order Hamiltonian which is symmetric with respect to intermolecular electron permutations shows better convergence than the procedures using nonsymmetric zero approximations. This conclusion follows from the calculations of ground state and four lowest excited states for three geometric configurations of the H4 system. The behaviour of the potential curves is interpreted in terms of symmetric perturbation theory. The various contributions to the interaction energy are considered in detail. The importance of charge transfer states for the description of the intermediate range of intermolecular separations is specially emphasized.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080312
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  • 160
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    A study of the symmetry dilemma: Second-order transitions (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 559-564 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transitions from symmetry-adapted to symmetry-broken solutions of variational problems are classified according to the nature of the discontinuity involved. Two systems in which a second-order transition occurs are studied.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080407
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  • 161
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    Masthead (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080501
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  • 162
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    The hammerstein integral equation: a general technique for constructing a rapidly convergent padé-type approximation to the logarithmic derivative (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 693-706 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radial one-electron Schrödinger equation can be written as a nonlinear first-order differential equation by making a suitable logarithmic transformation. The resulting Riccati equation has the equivalent Hammerstein integral representation [1], \documentclass{article}\pagestyle{empty}\begin{document}$$ \beta (r) = \int_{r' = 0}^\infty P(r') N(r,r')dr' \quad 0\buildrel{〈}\over{=} r 〈 \infty $$\end{document} where the kernel, N(r, r′) is \documentclass{article}\pagestyle{empty}\begin{document}$$ N\left( {r,\,r\prime} \right) = H\left( {r,\,r\prime} \right)\exp \left\{ {\int_{\xi = r\prime}^r {R\left( \xi \right)\beta \left( \xi \right)d\xi } } \right\} $$\end{document} and H(r, r′) is the Heaviside unit step function. This kernel is a more general one than that developed in ref. [1]. Both kernels apply in cases where the Riccati equation corresponds to a Sturm-Liouville problem.It is shown that this integral equation can be integrated by parts so that, for any local potential, the integrand decreases as the cyclic folding procedure is applied. During this cyclic folding, the kernel generates an equation that contains only coefficients of β(r)0 and β(r)1. Consequently, after truncating at the end of the nth cycle, it is possible to write down a Padé-type approximation to the logarithmic derivative as a known function of the independent variable. All coefficients in this approximation can be evaluated as simple algebraic formulations of P(r), R(r), and integrals over P(r).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080505
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  • 163
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    Symmetry in the Heitler-London method. II. The determination of the allowed molecular multiplets (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 171-177 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the framework of the Heitler-London method, a method for determining the allowed molecular multiplets is proposed. The method is based on the connection of the total molecular spin with the permutation symmetry of the coordinate wave function and on the isomorphism of the molecular point group with a certain subgroup of the electron permutation group. The method does not depend on the approximation in which the molecular ions are considered.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080204
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  • 164
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    Dual-basis orthonormality-constrained variation method (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 765-775 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method of orthonormality-constrained variation is extended using a dual-basis set instead of a single orthonormal basis. The complete and the partial variation methods are discussed and applied to electronic systems. It is found that the present formulation leads to the most general equation in the coupling operator method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080511
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  • 165
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    Method of complex molecular orbitals (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 799-816 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the spirit of Löwdin's extended HF scheme, an SCF method for the description of the molecular ground state, based on complex molecular orbitals, is developed. As a special case the method of parity mixing in orbitals is formulated. A calculational procedure for solving derived secular equations is described and numerical results, obtained in the minimal basis set, are reported for the N2 and CO molecule. Resulting ground state energies are close to the energies of the CI calculations with the same set of orbitals.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080515
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  • 166
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    Electronic correlation studies. II. Self-correlated field method. Application to ground state and first 1P, 3P excited states of two-electron atomic systemsAbstracted from part of a thesis submitted by R. Lissillour to the University of Rennes, 1973. (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 825-838 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An antisymmetric pair function can be built upon two kinds of monoelectronic functions, the former ones being correlated local functions and the second ones nonlocal functions taking external effects into account. This function, brought into the generalised product function procedure by means of the density matrix formulation, makes possible the study of correlation within N-electronic systems. The results of a first application of this method to the fundamental and to 1P and 3P excited states of two-electron systems are given.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080602
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  • 167
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    Configuration interaction calculations on the nitrogen molecule (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 61-72 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A contracted Gaussian basis set capable of describing about 63% of the correlation energy of N2 has been used in a detailed configuration-interaction calculation. Second-order perturbation theory overestimated the correlation energy by 23-50% depending on how H0 was chosen. Pair-pair interaction affects the correlation energy by about 20% while quadruple excitations have an 8% effect.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080106
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  • 168
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    Matrix elements for spin-adapted configurations (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 83-89 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that the turn-over rule which is used to simplify matrix elements between spin-projected Slater determinants may also be used to simplify formation of matrix elements between any orthonormal set of spin-coupled Slater determinants. The coefficients for the spin-coupling may then be chosen freely to reduce the number of important configurations in the secular equation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080109
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  • 169
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    Application of the distinguishable electron method (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 137-150 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to make a better assessment of the distinguishable electron method developed by Kirtman and co-workers, we have applied the method to some two-electron atoms and to H2 and LiH. Our results lend support to the contention held by Kirtman and co-workers that the distinguishable electron method is a practical way of calculating reasonably accurate physical properties.
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080114
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  • 170
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    Waller-Hartree spin-free method (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 523-537 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we show that with the equivalent transformation Pr = (-1)P(Pσ)-1 the spin function dependent methods such as Slater's method without group theory or Goddard's method with group theory differ only in different antisymmetric requirements from the present Waller-Hartree spin function free method. There exists a one-to-one correspondence between Slater's determinantal wave function and the Waller-Hartree double determinantal wave function. Explicit expressions for the S2 operator, Löwdin's spin projector, matric basis and several different forms of spin-projected functions are given for the Waller-Hartree formalism. The results are compared with other methods including those of Slater, Matsen, Gallup, Goddard and Segal. The differences are quite significant. New spin operators are worked out using creation-destruction operators. A knowledge of group theory is not required in this Waller-Hartree method. We have also shown that the Waller-Hartree method is more convenient than Slater's method with spin functions especially in the evaluation of the functional HΨ/Ψ. The advantages and disadvantages in the use of a linear combination of N! Hartree products and linear combinations of all possible double determinants are discussed. In addition, a formula for the calculation of the Sanibel coefficients C(S, M, i) is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080404
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  • 171
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    Nonbonded interactions in membrane active cyclic biopolymers. I. Valinomycin-potassium ion complexThe results of this paper were presented in summarized form at the Edward U. Condon International Symposium on Atomic, Molecular and Solid State Theory and Quantum Biology at Sanibel Island, Florida, U.S.A., January 1973. (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 565-583 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for quantitative comparison of various conformers of cyclic macromolecules in terms of nonbonded interaction energy terms is proposed. The first step in the procedure is an analytical evaluation of a set of Cartesian atomic coordinates consistent with the ring closure condition and prescribed values for internal parameters. A variant of the same technique enables different conformations of the macromolecule to be generated. Nonbonded interactions of the electrostatic, polarization and dispersion type and van der Waals repulsion are calculated using the generated coordinates, empirical bond polarizability data and results of simple molecular orbital calculations. An application of the proposed techniques to the closed symmetric conformation of valinomycin indicates that the macromolecule by itself is somewhat constrained in this state but that its affinity for a potassium ion is very strong - much stronger than the hydration energy of the latter.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080408
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  • 172
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    Intermediate problems for eigenvalues (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 623-625 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080412
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  • 173
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    Ab initio calculations on urea (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 857-892 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multiconfiguration wave functions constructed from contracted Gaussian-lobe functions have been found for the ground and valence-excited states of urea. ICSCF molecular orbitals of the excited states were used as the parent configurations for the CI calculations except for the 1A1(π → π*) state. The 1A1(π → π*) state used as its parent configuration an orthogonal linear combination of natural orbitals obtained from the second root of a three-configuration SCF calculation. The lowest excited states are predicted to be the n π → π* and π → π* triplet states. The lowest singlet state is predicted to be the n π → π* state with an energy in good agreement with the one known UV band at 7.2 eV. The π → π* singlet state is predicted to be about 1.9 eV higher, contrary to several previous assignments which assumed the lowest band was a π → π* amide resonance band. The predicted ionization energy of 9.0 eV makes this and higher states autoionizing.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080604
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  • 174
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    Spin-orbit interaction in polyatomic molecules: Ab initio computations with Gaussian orbitals (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 941-950 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Standard sets of Gaussian atomic orbitals (STO-3G, STO-4.31G) are used to evaluate spin-orbit coupling constants in linear molecules (CO2+, NNN) and spin-orbit effects on singlet-triplet transition intensities in formaldehyde. All spin-other orbit effects have been included. In all cases spin-other orbit interactions form a large fraction of the matrix elements. Simple formulae to evaluate spin-orbit one- and two-electron integrals over atomic orbitals are presented. Standard molecular integral programs can be used for the computation of spin-orbit integrals.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080609
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  • 175
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    Error analysis of variationally optimized upper- and lower-bound wave functions for H2+Work supported in part by the National Research Council of Canada. (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 971-980 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Wave functions which are a linear combination of H2+-type elliptical orbitals are optimized to provide either an upper bound or a lower bound to the H2+ ground state. For the latter, Temple's formula is used. Three criteria are considered to determine the relative accuracy of these wave functions: (i) energy (calculated versus exact eigenvalue); (ii) average error; and (iii) local energy. Although the lower-bound optimized wave functions obtained are the most accurate available for H2+ from approximate wave functions, they are still inferior to the corresponding upper-bound wave functions by criteria (i) and (ii). In particular, using criterion (ii), it is shown numerically that the upper-bound functions are “correct to second order,” while the lower-bound functions are almost, but not quite, “correct to second order.” Despite this, the local energy analysis, criterion (iii), reveals that the lower-bound wave functions can be more accurate than the upper-bound functions in some regions of space, and hence give more accurate values for physical properties sensitive to these regions. Examples considered are the dipole-dipole and Fermi contact interactions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080611
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  • 176
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    Variation of the polarizability of the hydrogen molecule ion and the hydrogen molecule with internuclear separation (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 91-95 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variation of the polarizability of H2+ and H2 with internuclear separation R = 1.6 - R = 2.4 a.u. for H2+ and R = 1.0 - R = 2.0 a.u. for H2 is determined using a variational method suggested by Das and Bersohn. From these data, values of 〈α〉0,J for which nuclear motion due to zero point vibration and centrifugal stretching is taken into account, are calculated at 300°K. The relative percent increases of the motion averaged values compared to the equilibrium values are as follows: 10.50% for H2+ and 6.52% for H2.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080110
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  • 177
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    Floating one-center perturbation treatments for H2+-like molecules based on screened hydrogen atom or molecular puff unperturbed problems (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 119-136 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various floating one-center perturbation schemes are developed for H2+-like molecules. Previous work for the ‘1s’ hydrogen atom approach is extended through third order in the energy. In the molecular puff approach an exact ‘closed form’ solution is obtained for the zeroth-order problem, which corresponds to a double layer molecular puff. Semianalytical results for the first-order correction to the floating molecular puff wave function and for the energy through third order are developed which offer a convenient alternative to previous approaches. Explicit calculations for ground state H2+ show that for R 〉 3aO the ‘1s’ and the more complicated ‘puff’ treatments are equivalent and that neither the ‘1s’nor the molecular puff function is an adequate zeroth-order wave function for the important intermediate values of R. The usefulness of some of these methods in a variety of problems, where one-center zeroth-order wave functions do appear to be adequate, is discussed briefly.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080113
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  • 178
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    Accurate analytical self-consistent field wave functions for Tm2+ and Tm3+ (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 73-78 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analytical expansion self-consistent field method was employed to perform ab initio calculations for the ground states of the rare-earth ions, Tm2+, 4f13, 2F, and Tm3+, 4f12, 3H, (Z = 69). In each case the total number of basis functions used in the analytical expansions was 29, distributed as follows: 10, 8, 5, and 6, for the symmetries s, p, d, and f, respectively. All of the orbital exponents of the basis functions were optimized repeatedly, to the extent of the single-precision computer representation. Values of 〈rn〉 for the 4f orbital of both ions are also presented, for the convenience of experimentalists.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080107
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  • 179
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    Coupled Hartree Fock calculation of static dipole polarizabilities and shielding factors of open shell systems (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 97-105 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Static dipole polarizabilities and shielding factors for the 2p open shell atomic systems are presented using coupled Hartree Fock theory in the framework of the Roothaan formalism. Calculations have been performed for the ground as well as for some valence excited states. A variational approach has been adopted for the determination of the first-order perturbed functions. The results are compared with those obtained from the correlated calculations and other techniques. The shielding factor values are in excellent agreement with the theoretical N/Z ratio.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080111
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  • 180
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    Extended Hartree-Fock self-consistent field with some results for berylliumlike atomic systems (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 839-855 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The general methods of deriving the extended Hartree-Fock equations are described. The rules for going over from the energy expression in the ordinary method of calculation to that in an extended one are reformulated and illustrated. The extended Hartree - Fock equations for berylliumlike atomic systems based on the use of nonorthogonal radial orbitals are given and solved. The numerical values of overlap integrals and total energies are given and discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080603
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  • 181
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    Dynamic polarizability of helium: A random phase approximation calculation (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 901-913 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The random phase approximation (RPA) or time-dependent Hartree-Fock approximation (TDHF) is reconsidered for the calculation of the dynamic polarizability for atoms. An integral equation which admits a simple numerical treatment is established. The asymptotic approximation for the electron propagator is tested for its applicability by means of comparisons with earlier results.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080606
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  • 182
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    Book Reviews (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 995-995 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080613
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  • 183
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    Molecular integrals over generalized gaussian basis sets (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 179-191 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is given for obtaining the common molecular integrals over generalized gaussian functions: \documentclass{article}\pagestyle{empty}\begin{document}$$ \chi_i = x^{\lambda_i}_i \exp \big\{ - \big(\alpha_i x^2_i + \alpha^{\prime}_i x^{\prime 2}_i + \alpha^{\prime\prime}_i x^{\prime\prime 2}_i\big)\big\} $$\end{document}The present algorithms are expected to be more efficient than those given in earlier work by the same author.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080205
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  • 184
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    On the need of precision in the calculation of the LCAO density matrix of polymers (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 201-208 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper, we point out how the precision of the LCAO density matrix elements of polymers may affect the computed properties. We propose to use a more adapted approach in order to evaluate these quantities.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080207
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  • 185
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    The Coulomb hole in the 23S state of the helium isoelectronic sequence (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 255-261 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pair distribution functions evaluated for the 23S state of the helium isoelectronic sequence from the Hart and Herzberg correlated wave functions and those corresponding to the Hartree-Fock approximation are used to determine the shape of the corresponding Coulomb holes. As a consequence of a discontinuity in the Hartree-Fock solution between He and Li+, the Coulomb hole has a different shape for He than for Li+ and the other isoelectronic ions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080212
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  • 186
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    Oscillator and hydrogenic matrix elements by operator algebra (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 585-604 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Occupation number representation of the two-dimensional harmonic oscillator and some operator formulae are used in a simple algebraic derivation of complicated integrals. The calculation of full oscillator- and radial integrals of r̂w and exp (\documentclass{article}\pagestyle{empty}\begin{document}$ (iw\hat{\varphi})$\end{document}), where w is an arbitrary positive or negative integer, are performed by an integral transform, leading to a generalized Gauss matrix element. Thus it is possible, because of the back transformation, to derive from one generalized Gauss matrix element all matrix elements which are permitted by the selection rules. Some integrals of r̂w and exp (\documentclass{article}\pagestyle{empty}\begin{document}$ (iw\hat{\varphi})$\end{document}), Laguerre polynomials, and Bessel functions are completely new. For the already known integrals, the mathematical labour is considerably reduced. The relation between the two-dimensional oscillator and the hydrogen atom and their angular momentum properties are discussed. A survey on the various methods applied to the oscillator problem, from complex integration to noncompact Lie groups, and a comprehensive bibliography on this important spectroscopic field are given.
    Additional Material: 604 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080409
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  • 187
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    Electron correlation study for two-electron atoms by a simple correlated wave function (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 755-764 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The difference in the electron correlation between H- and other two-electron atoms is clarified by the introduction of the r12 term in the wave function. By using the expansion of r12, a certain modification of the usual electron correlation factor 1 + Cr12 is introduced and its effectiveness is examined. Calculations are carried out for the ground state and the three lowest excited states (23S, 23P and 21P). The peculiar electron correlation in the ground state of H- is shown by looking at the Coulomb hole for closed- and open-shelf models in comparison with those for other two-electron atoms.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080510
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  • 188
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    Virtual orbital transformation prior to configuration interaction with localized orbitals (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 777-782 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A virtual orbital transformation is proposed involving pairing of localized occupied orbitals with virtual orbitals. The virtual orbitals are transformed so that each virtual orbital is as “close” as possible to its occupied counterpart, where closeness is the inverse of the particular definition of localization. The appropriate transformation is derived for the special case of Foster-Boys localization, and an illustrative CNDO/2 calculation on HNO is presented. INDO CI results on the series N2, CO, BF indicate that use of this transformation may reduce the number of energetically significant configurations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080512
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  • 189
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    Molecular orbitals of nitrogen at small internuclear distances (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 817-821 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080516
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  • 190
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    Masthead (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080601
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  • 191
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    Perturbative ab initio calculations of intermolecular energies. I. Method (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 1-15 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from a knowledge of approximate wave functions of the isolated molecules (or atoms) A and B, a method is proposed to build up a zeroth-order ground state and excited configurations for the complex AB in which the molecular orbitals keep their local significance. The standard Rayleigh-Schrödinger perturbation in this basis provides a decomposition of the zeroth-order interaction energy as a sum of the electrostatic and repulsion energy. In the second order, it is possible to identify the classical dispersion and polarization forces (modified by a term of order S2) and two additional contributions which are linked to the exchange possibility. The intramolecular correlation component is taken into account and compared with the correlation on the isolated molecules. It is moreover suggested that since we work in a rather limited basis set, the perturbed energy of AB must be compared with the unperturbed energies of A and B calculated in a basis including the vacant orbitals on their respective partner. Finally a possibility for going beyond the second order is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080102
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  • 192
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    Matrix formulation of the generalized Hartree-Fock methods (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 45-60 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spin-projected one-particle density and spin density matrices are presented as polynomials of suitable unprojected quantities with generalized Sasaki-Ohno coefficients. Thus an explicit form of Harriman's theorems is given. For the two-particle spatial density matrix an expansion in direct products of powers of unprojected residual electron and spin density matrices is given. For these basic matrices of the scheme the variational spin-extended equations are formulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080105
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  • 193
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    Symmetry adaptation and the relation between the spin-free and space-spin formulations of electronic structure (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 223-233 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An information-theoretic degree of symmetry adaptation of a ket with respect to a given group is introduced. Then the general equivalence between spin-free electronic kets and antisymmetrized space-spin kets is obtained so long as our attention is restricted to spin-independent observables. It is noted that there are spin-free kets for which there exists no single antisymmetrized space-spin ket giving all the same expectation values; the converse is also noted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080209
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  • 194
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    Transformation properties of many-electron wave functions with special attention to the relation between pair-correlated DODS and configuration interaction (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 715-732 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is presented that leads to a simple derivation of the explicit relation between pair-correlated DODS schemes (e.g., the alternant molecular orbital method and the extended valence bond method) and configuration interaction.This result is based on a reduction formula for the representations of the general linear group, GL(m), carried by the N-electron function space. Generally, this paper deals with the effect of “partitioned” orbital transformations on states with “local” permutation symmetry.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080507
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  • 195
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    Ab initio calculations on porphin (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 915-924 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio SCF calculations are reported for the porphin molecule. The positions of the central protons have been optimized, and the equilibrium geometry is found to be a linear NH ⃛ HN arrangement. The NH vibrational frequencies have been computed and are compared to experimentally measured quantities. Several low ionized states have also been studied in separate spin-restricted SCF calculations. The lowest state is found to have B1u symmetry with an ionization potential of 8.0 eV.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080607
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  • 196
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    Basis dependence of wave functions of the ground state and low-lying excited states of planar formaldehydeThis is a part of a thesis for the Ph.D degree conferred by the Hokkaido University. (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 981-993 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By the use of three bases containing 3p STO's possessing different diffuseness, the electronic structure of several excited states (valence- and Rydberg-type) of planar formaldehyde is investigated by limited CI calculations. The spatial extension of the valence-type state is independent of the bases, whereas a diffuse orbital is important in describing the Rydberg-type state. The natural orbital analysis shows that the Rydberg-type states can be described as an outer electron plus an electronic cloud representing the ionized state to which the Rydberg states converge.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080612
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  • 197
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    Electronic Resource
    Masthead (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080101
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  • 198
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    Perturbative ab initio calculations of intermolecular energies. III. The water dimer (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 29-43 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction energy between two water molecules A and B is calculated by the method described in Paper I [1], previously applied for the interaction between two helium atoms (Paper II) [2]. This interaction energy is obtained as the difference between the energies of the complex (A + B) and the monomers (A) and (B), obtained by a perturbation method. The results obtained with the perturbation developed up to the second order in a minimal atomic basis set are decomposed into classical contributions and contributions linked to the exchange possibility. Charge transfer contributions are important and the localized character of the hydrogen bond is examined. It is pointed out that the definition of the set of excited configurations for the calculation of the energies of the isolated monomers is important, especially when one tries to use a small atomic basis set. A similar effect in SCF-type calculations is evaluated. The contribution of higher orders is evaluated by the CIPSI method.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080104
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  • 199
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    Electronic Resource
    Alternative equivalent icosahedral irreducible tensors (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 153-161 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some sets of icosahedral irreducible tensors can only be defined with respect to one of two seemingly equivalent choices of axes. The problem is explained and the cases when such an alternative choice may cause mixing of sets belonging to different irreducible representations are determined. It is found that the amount of mixing is a property of the spherical basis sets and is independent of the rank and of the permutation symmetry of the tensorial sets. It is further found that certain operators which change the handedness of the coordinate axes can similarly affect these sets, notwithstanding the centrosymmetry of the icosahedron.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080202
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  • 200
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    Structure de l'ion fluoronium FH2+ et chemin de la protonation du fluorure d'hydrogeneTravail préasentéea à l'occasion du Premier congrès international de chimie quantique (4-10 juillet 1973, Menton, France) (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 8 (1974), S. 193-200 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of the ion FH2+ is investigated on the basis of semiempirical (INDO) and nonempirical (extended gaussian basis set) calculations. In agreement with experiment, both methods predict that, when going from FH to FH2+, there is a lengthening of the F—H bond; also in agreement with infrared analysis, the calculations indicate a bent structure for the fluoronium ion (valence angle at about 120°). The analysis of the FH protonation path reveals the existence of a potential barrier which is exclusively produced by solvation effects; the dependence of the proton affinity of FH on the dielectric constant of the reaction medium is also discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560080206
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