Library

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (413)
  • 1965-1969
  • 1987  (275)
  • 1985  (138)
  • Atomic, Molecular and Optical Physics  (413)
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 475-485 
    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 present a coupled-cluster polarization propagator method based on a coupled cluster singles and doubles reference state. Applications to the Be atom show that we may calculate electronic excitation energies with an average absolute error of about 0.08 eV using this method. We have also calculated the nuclear spin-spin coupling constant of 1H19F to be 524.4 cps, in good agreement with experiment. For Be there is a large effect of using coupled-cluster rather than a low-order Rayleigh-Schrödinger expansion, whereas the coupling constant of HF is less sensitive to this improvement in the reference state.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 102
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 435-456 
    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 discuss the properties of a phase space distribution function that can be expressed as a Gaussian convolution of the Wigner function corresponding to the oneelectron charge density matrix for a many-electron system. This distribution function is known as the Husimi function. It is real and nowhere negative and can be interpreted as a probability density for finding an electron in a particular coherent state or, equivalently, for finding it in a region of phase space consistent with the uncertainty principle. Information is not lost in the transformation from the Wigner function, which can be recovered. We discuss the relationships among various functions and their Fourier transforms. The Husimi function does not have the ordinary densities as marginals but rather Gaussian convolutions of them, from which the ordinary densities can be recovered. Advantages of the Husimi function over the Wigner function for the interpretation of electronic structure are discussed. Illustrative results for the hydrogen atom and for the nitrogen atom at the SCF level are presented.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 103
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 547-554 
    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 original formulation of the MNDO method, the approximation of two-center two-electron integrals over p orbitals is not rotationally invariant, and the coulombtype integrals do not match their one-center counterparts. In recent computer codes the rotational invariance has been restored by dropping the original approximation for two-center exchange integrals over π orbitals, which at the same time disconnected these too from the one-center values. It is shown in this paper that the rotational invariance problem can be overcome in the framework of the original approximation. It is also demonstrated that the mismatch between the one- and two-center two-electron integrals may be the reason for the too short Si-Si bond lengths predicted by MNDO.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 104
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 573-587 
    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 quantum path integral molecular dynamics method was utilized to explore the compositional, structural, and size dependence of localization mode of an excess electron in ionic and hydrogen-bonded clusters, providing information on the nature of surface states and on isomerization induced by electron attachment in large finite systems.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 105
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 595-602 
    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: Properties of the ground state (X 1Σ) of the BCl molecule are calculated in complete fourth-order many-body perturbation theory. The equilibrium bond distance is determined to be Re = 1.740 Å (Re(exp.) = 1.716 Å). Spectroscopic constants are evaluated from the potential curve and agree well with available experimental data. Static electric properties are computed by the finite-external-electric-field perturbation method. Apparently, no experimental information on these properties is available. Fully numerical Hartree-Fock results are used to estimate basis-set effects on the calculated quantities.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 106
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 669-676 
    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: While calculating zero-field splitting terms for the lowest triplet state of 4H-pyran4-thione, at the experimental geometry, it was found that the ground state was unstable with respect to an unrestricted Hartree-Fock perturbation. The smallest fragment of the molecule retaining this instability was found to be diatomic CS. The instability is dependent on the basis set used for the calculation. The instability and its relationship to basis set, equilibrium geometry, and the importance of polarization functions for second row elements has been explored for CS and H2CS as a function of internuclear distance. Minimal basis set calculations involving second row elements may be particularly prone to such instabilities.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 107
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 693-698 
    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 displaced STO can be expanded in spherical harmonics with the coefficient functions or Löwdin a functions characterized by a C matrix. These α functions themselves may be expanded in a Taylor series that is characterized by its own E matrix. This expansion is necessary for the representation of the α function by a power series and for its evaluation about the origin. As an application, we find the power series for the molecular charge density in the vicinity of the center of a model diatomic molecule. Our analytic approach is general and yields excellent results.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 108
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 743-748 
    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 studied the IR multiphton excitation and dissociation process of a Morse oscillator driven by an external sinusoidal field. Primary resonances and an infinite sequence of secondary resonances have been found that can be analyzed by using Chirikov's nonlinear resonance theory. The transition threshold to global stochasticity is also estimated based on the overlap criterion. Above the threshold dynamical flows are slowed down by the presence of cantori, as clearly demonstrated by the time-dependent dissociation rates calculated for several ensembles of initial points. A scaling law is found in the vicinity of the threshold with a critical exponent in close agreement with that predicted for the standard map.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 109
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 761-762 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 110
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 991-991 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 111
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 501-509 
    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: Based on the use of the important qualitative concept of energy-weighted averages, a few simple rules are formulated that facilitate the analysis of the existence of surface states and enable the estimation of the effect of surface charge self-consistency on the electronic structure of AB-type crystal surfaces. Recent theoretical and experimental investigations of the (001) and (111) surfaces of refractory transition metal compounds TiC and TiN are discussed in detail. The problem of the stability of the polar (111) surface of TiC is mentioned.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 112
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987) 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 113
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 613-620 
    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: Rayleigh-Schrouml;dinger (RS) perturbation expansions for the eigenvalues E(λ) of a hydrogen atom in the general polynomial perturbation V(r) = aλr + b〉2r2, a, b 〉 0, are studied. When a2 = 2b, the ground state energy is exactly E(λ) = -(1/2) + (3/2)a〉, i.e., the RS series is truncated. In the case a2 〉 2b, the RS series is negative Stieltjes. In general, when λ 〈 0, a well of depth ω ≈ -a2/(4b2) (note the λ independence) is situated at rω = a/(2b|λ|). When a2 〉 2b/N2, and interaction between this well and the hydrogenic state ψNLM(λ) is possible, thus creating a pair of asymptotically degenerate eigenstates separated by a “gap” δE(λ). The large order behavior of the RS coefficients ENLM(n) may be computed from the asymptotics of δE(λ), which is, in turn, related to the tunnelling integral. For excited states, stricter inequalities must be obeyed for Stieltjes behavior. The E(n)NLM may be calculated either numerically or in closed form via the “so(4, 2) Lie algebra technology” for such hydrogenic problems.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 114
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 3-7 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 115
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987) 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 116
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 45-55 
    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 new method is presented to analyze the IGLO (individual gauge for localized orbitals) bond contributions in 13C chemical shielding. The IGLO bond contributions calculated in the molecular frame are rotated to a local bond frame, in which one component is selected along the bond. This procedure removes the explicit angular dependence of the IGLO bond contributions and allows a comparison of the bond contributions in different molecules.The results provide a new method to study the electronic basis of shielding interactions. The problems associated with the multiple gauge origins used in the IGLO method are discussed in their relationship to the bond contribution analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 117
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 17-31 
    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 have calculated reaction rates for the reactions O + HD → OH + D and O + DH → OD + H using improved canonical variational transition state theory and least-action ground-state transmission coefficients with an ab initio potential energy surface. The kinetic isotope effects are in good agreement with experiment. The optimized tunneling paths and properties of the variational transition states and the rate enhancement for vibrationally excited reactants are also presented and compared with those for the isotopically unsubstituted reaction O + H2 → OH + H. The thermal reactions at low and room temperature are predicted to occur by tunneling at extended configurations, i.e., to initiate early on the reaction path and to avoid the saddle point regions. Tunneling also dominates the low and room temperature reactions for excited vibrational states, but in these cases the results are not as sensitive to the nature of the tunneling path. Overbarrier mechanisms dominate for both thermal and excited-vibrational state reactions for T 〉 600 K. For the excited-state reaction (with initial vibrational quantum number n 〉 0) a transition state switch occurs for T 〉 1000 K for the O + HD(n = 1) → OD + H case and for T 〉 1500 K for the O + DH(n = 1) → OD + H reaction, and this may be a general phenomenon for excited-state reactions at higher temperature. In the present case the switch occurs from an early variational transition state where the vibrationally adiabatic approximation is expected to be valid to a tighter variational transition state where nonadiabatic effects are probably important and should be included.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 118
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 81-90 
    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 balanced addition of polarization functions to the 6-31G and 6-311G basis sets for correlated wave functions is evaluated using bond energy predictions at the MP2 and full MP4 levels as a measure of correlation-balanced basis sets. The homolytic dissociations of the XH bonds in H2, CH4, NH3, H2O, and HF and the XY bonds in C2H6, NH2NH2, HOOH, and CH3OH are used as the basis for the evaluation. It is found that correlation balance is achieved for HH, XH, and XY bonds, particularly at the MP2 level, only if at least as many polarization sets, and sometimes more, are added to the hydrogens as are added to the heavy atoms.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 119
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 119-131 
    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: Rotational motion can have a significant effect on intramolecular vibrational dynamics. In this paper, we explore the recently discovered phenomenon of rotational decoupling through both quantum mechanical and classical methods. It is found in a model system for the stretching motions of HDO, that rotational motion about the c axis can decouple the stretches. This fact can be understood as a cancellation between kinetic and centrifugal coupling as illuminated using classical resonance analysis and quantum matrix element calculations. The significance of this phenomenon is discussed in infrared multiple photon absorption experiments with specific application to isotope separation in HDO.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 120
    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 developed a theoretical method for studying the aromatic stability of large molecules, molecules having a dozen and more fused benzene rings. Such molecules have so far often been outside the domain of theoretical studies. Combining the statistical approach and a particular graph theoretical analysis, it is possible to derive the expressions for molecular resonance energy for molecules of any size. The basis of the method is enumeration of conjugated circuits in random Kekulé valence structures. The method has been applied to evaluation of the resonance energies of conjugated hydrocarbons having about a dozen fused benzene rings. The approach consists of (1) construction of random Kekulé valence structures, (2) enumeration of conjugated circuits within the generated random valence structures, and (3) application of standard statistical analysis to a sufficiently large sample of structures. The construction of random valence forms is nontrivial, and some problems in generating random structures are discussed. The random Kekulé valence structures allow one not only to obtain the expression for molecular resonance energies (RE) and numerical estimates for RE, but also they provide the basis for discussion of local molecular features, such as ring characterization and Pauling bond orders.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 121
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 123-131 
    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 isomers of CH3(H2O)n+ (where n = 1-3) have been studied using self-consistent field gradient techniques. The calculations have largely employed a split valence (4-21G) basis set, although the effects of polarization functions and electron correlation have been considered for a model system. A mechanism for the formation of CH3OH from CH3(H2O)n+, involving linear hydration chains, is proposed, and the relevance of the results to the various proposed pathways for the decomposition of nitrosamine metabolites is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 122
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 165-179 
    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 path codes are computed for 17 hydrocarbons, including benzenoid alternant, nonbenzenoid alternant, fully aromatic nonalternant, antiaromatic nonalternant, and monoradical hydrocarbons. Comparability conditions of Randić and Wilkins [9-18] based on the theorems of Muirhead and Karamata are imposed on the partial sums of the codes. The distance/similarity matrix is constructed using the individual paths as projections in Euclidean space. Both resonance energies and total pi energies correlate with partial ordering predicted from both comparability and similarity schemes. The normalized codes succeed in discriminating combinatorial properties of the various topologies studied such as conjugated circuits.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 123
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 279-293 
    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: Electrostatic, exchange, classical induction, and charge-transfer components of the He2 interaction energy have been analyzed within our previously proposed SCF interaction energy decomposition scheme [36] employing full counterpoise correction of the basis set superposition error (BSSE). The results have been supplemented by dispersion energies evaluated within the variation-perturbation approach. The basis sets used here have been systematically increased in order to investigate basis set extension effects and perform a thorough test of our decomposition scheme. The results obtained for He2 at its van der Waals minimum (R = 5.6 a.u.) indicate that interaction energy components corrected by the full counterpoise method display reduced basis set dependency, do not seem to be overcorrected by the Jansen-Ros-Boys-Bernardi approach, and converge toward the most accurate values available in the literature. The correct representation of occupied orbitals in He requires the use of at least 1s primitive is Gaussian orbitals. This explains the inconclusive character of previous attempts to resolve the BSSE overcorrection problem within smaller expansions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 124
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 377-396 
    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 earlier-proposed perturbative approaches to the description of weakly interacting species are considered. It is argued that most of these perturbative approaches, including many of the so-called exchange perturbation theories, exhibit a number of difficulties and limitations, which have not previously been emphasized. From these criticisms positive suggestions as to the nature of a general exchange perturbation-like theory are made. Finally, a candidate for such a theory is outlined.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 125
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 407-408 
    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: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 126
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 405-406 
    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: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 127
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 417-424 
    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: Pair coupling between a chiral molecule and an achiral molecule can induce weak circular dichroism in the achiral partner, as is well known in induced circular dichroism. Here the effect of the same coupling on the chiral partner is analyzed. The effect is an increase or decrease in the rotatory strength that may be detectable under conditions where the effect is enhanced by a near-resonance.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 128
    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 computational procedure for reconstructing a many-electron wave function on the basis of x-ray diffraction data of one-electron density is proposed within the method of local-scaling transformations.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 129
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 411-426 
    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 report a model calculation of the transport of a local (site) excitation in a doped molecular crystal containing one impurity. We do not consider the impurity as a direct trap for electronic excitations (zero trap depth) but assume that exciton-phonon interaction is exclusively given by the coupling of excitons with the vibrational displacement of the impurity. The dynamical problem is solved by using a time-dependent effective potential consisting of equilibrium average exciton-phonon interaction and fluctuations around this average. Two correlation functions are computed using the slow phonon limit and assuming that the temperature of the system is 300 K.Transmission of the excitation energy over a distance of eight spacings takes place, electronically, within a few picoseconds. With the exciton-phonon interaction switched on, calculated correlation functions diminish very rapidly with increasing time, indicating that an irreversible transfer of excitonic energy to the thermal bath takes place. Thus transmission of the excitation energy over such a distance (and without a high rate of trapping) is not an efficient process.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 130
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 429-433 
    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 greatest single success of modern computational quantum chemistry has been its ability to correctly predict the geometrical structures of molecules. The FOOF molecule stands in contrast to the overwhelming mass of comparisons between theory and experiment. This research shows that configuration interaction (CI) methods including all single and double excitations (SD) fail to predict the correct FOOF structure, even when high-quality basis sets are employed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 131
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 451-456 
    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 entity of generalized Rayleigh's quotient is introduced. A formalism involving calculation of the functional gradient and Hessian of the quotient reveals several properties that lean on the variational approach to the direct optimization of the ground state wave function. In particular, the link between a minimization of the generalized quotient and the solution to the “nonlinear Schrödinger equation” is elucidated. The concept of functional derivatives enables us to perform a direct optimization of the trial ket through the Newton-Raphson or the augmented Hessian method. Eventually, a “universal” perturbation theory is derived.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 132
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 563-574 
    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 double many-body expansion (DMBE) method has been applied to the many-valued ground-state potential energy surfaces from three and four interacting 2S atoms. New forms are suggested where the degeneracy manifold of the two Riemann sheets of the potential surface can be made identical to that predicted from the London equation that is correct to first-order. Considerable flexibility can be introduced through adjustable coefficients to fit ab initio data, whereas the potential energy terms can be chosen to maintain the correct analytic properties at the conical intersection. Hence, the new forms may be used on the extrapolation of the potential energy from the lowest- to the upper-Riemann sheets. Long-range effects are semiempirically described from the general formalism of the DMBE method.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 133
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 549-549 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 134
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 551-562 
    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: Pair-excitation multiconfigurational self-consistent field (PEMCSCF) treatment of 11 small molecules (LiH, BeH2, BH3, BF, CH4, C2H4, C2H2, CH2O, NH3, H2O, and HF) has been carried out in a minimum basis set of Slater Transform Preuss functions as fitted by six cartesian gaussians (STP-6G). The advantages of accuracy without using a split basis are shown by comparison to familiar 4-31G and 6-31G calculations using molecular geometries optimized with STO-6G basis sets. A benefit is shown for the use of minimum basis fitted to STP functions: they overemphasize long-tail radial dependence to achieve long range basis sensitivity without increasing the basis size at the AO-to-MO transformation step in the configuration interaction portion of the MCSCF algorithm. Fully optimized STP-6G parameters are given and appear to be transferable as shown for acrolein. A FORTRAN listing of the full least squares fitting algorithm is available* for in situ generation of STP-6G orbitals energetically superior to 4-31G, or a less accurate STP-6G 1S, 2S, and 2P basis may be scaled directly as if they were STO-6G functions, but with considerably lower energy that with an STO-6G basis.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 135
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 575-589 
    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 avoid the determination of the perturbed wave function in the susceptibility calculation of closed shell molecules, several authors have developed gauge-variation methods based on Rebane's work. The present work illustrates that introduction of a certain restriction in the gauge-variation method makes the susceptibility calculations exceptionally simple. The restriction involves the use of the Coulomb gauge so that the gauge-function satisfies Laplace's equation. The restriction was dictated by the demonstration of gauge-invariance of the Rayleigh-Schrouml;dinger perturbation theory of diamagnetism. The method with the prescribed restriction has been applied to the H2O molecule, as an example, to demonstrate the advantages.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 136
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 621-653 
    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-independent alternant systems are analyzed using the alternancy symmetry adapted (ASA) approach. This approach is based on an explicit construction of ASA operators that either commute (altemant) or anticommute (antialternant) with the particle-hole symmetry operator K̂. The method yields an explicit construction and identification of all spin-independent Hamiltonians that describe altemant systems (neutral and/or ionic) as well as an explicit identification of all linear properties characteristic to these systems. It also establishes the connection between the spin-eigenstates and the particle-hole symmetry.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 137
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 521-534 
    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 increasing rate at which improvements in processing capacity outstrip improvements in input/output performance of large computers has led to recent attempts to bypass generation of a disk-based integral file. The “direct” SCF method of Almlöf and co-workers represents a very successful implementation of this approach. The present work is concerned with the extension of this general approach to CI and MCSCF calculations. After a discussion of the particular types of MO integrals for which  -  at least for most current generation machines  -  disk-based storage seems unavoidable, it is shown how all the necessary integrals can be obtained as matrix elements of Coulomb and exchange operators that can be calculated using a direct approach. Computational implementations of such a scheme are discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 138
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 507-520 
    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: Multireference configuration interaction (MR-CI) calculations using energy-selected and complete-active-space reference configurations are compared for a large-basis-set treatment of the (H2)2 van der Waals complex in a T geometry. Procedures for estimating truncation errors arising from energy threshold selection of configuration state functions and for extrapolating to the full CI limit are tested by comparisons with untruncated calculations and with the full CI energy. The results of these tests show that great care is required in the use of the correction and extrapolation formulas. Optimization of the orbitals of the reference wave function (compared to the use of SCF orbitals) is found to produce order-of-magnitude improvement in the results.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 139
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987) 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 140
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 535-563 
    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 construct bases for the irreducible representations of the rotation group O(3) which are symmetry adapted to a Crystallographic point group. We obtain explicit expressions for the cubic groups, which are valid for arbitrary values of the angular momentum quantum number l. Our method yields an efficient algorithm for both analytical and numerical work. An explicit formula for the multiplicities of an irreducible representation for the cubic groups in an arbitrary angular momentum term l is also derived.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 141
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 565-567 
    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: Two-center Coulomb and hybrid integrals are combined into a single expression by use of the formulas given by the author for the expansion of real and complex STO's about a point displaced from the orbital center. The final results are expressed in terms of the overlap integrals between STO's. Analytical formulas for the evaluation of these integrals have been established recently by the author.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 142
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 581-590 
    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 spectral density operator technique is proved to be a convenient tool for derivation of approximate topological formulae for total pi-electron energy (Epi) of benzenoid hydrocarbons (BHs). Developed mathematical formalism points out a common origin of three different measures for the stability of BHs, namely: resonance energy (RE), number of Kekule structures (K) and HOMO-LUMO separation (XHL). In turn, a novel topological invariant corresponding to “normalized” RE is derived. Numerical calculations for a representative set of BHs demonstrate effectiveness of the present approach. Various approaches to an estimation of BH stabilities are discussed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 143
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 569-579 
    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: There is considerable evidence indicating that the primary in vivo DNA alkylation product of vinyl chloride, believed to be responsible for its carcinogenicity, is the 7-N-(2-oxoethyl) derivative of guanine. Using a representative keto-enol system, we have studied computationally two possible equilibria involving this adduct. The first is between the 2-oxoethyl derivatives of the keto and enol forms of the representative system, whereas the second is between the 2-oxoethyl derivative of the keto form and the corresponding hemiacetal. In the case of the analogous guanine derivatives, such equilibria could lead to disruption of the hydrogen bonding between guanine and cytosine in DNA and could cause miscoding and replicational and transcriptional errors. An ab initio self-consistent field molecular orbital study has been carried out using the GAUSSIAN 82 system of programs. Optimized structures and energies have been calculated at the 2-21G level for the representative keto-enol system and its 2-oxoethyl and hemiacetal forms. The formation of the 2-oxoethyl adduct was found to have no significant effect upon this keto-enol equilibrium, which strongly favors the keto form. Our calculations further show hemiacetal formation to be an unlikely possibility for this system. On the basis of these results and recent data on guanine tautomers, we speculate about the analogous equilibria involving the guanine derivatives.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 144
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 591-603 
    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 CI space Xn generated by n electrons moving over 2n spin orbitals is considered. It is shown that the transitions between different eigenstates ψi ∊ Xn of alternant and weakly alternant Hamiltonians are governed by some special selection rules. These selection rules are characteristic to alternant systems, and they do not apply to nonalternant systems. The set of all such selection rules can be easily derived from the splitting theorem. In particular, the selection rules associated with spin independent alternant systems are considered. As an example, the PPP Hamiltonian Ĥp describing netural alternant hydrocarbons is treated. In the case of electron dipole transitions between eigenstates ψi ∊ Xn of the Hamiltonian Ĥp, the selection rules obtained are in agreement with the selection rules derived previously by Pariser and McLachlan.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 145
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 605-609 
    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 asymptotic formula describing a dependence of the algebraic structure count (ASC) of the even-membered rotagraphs on its size (N) is derived from the backfolding theorem for the electronic band structure. This new result imposes very strict constrains on ASC as a function of N.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 146
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 3-11 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 147
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 55-64 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 148
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 65-72 
    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: Transition metal impurities in tetrahedral semiconductors are discussed, with emphasis on electronic structure results. The trends with atomic number within the 3d series, and down-the-column trends for 4d and 5d metals in III-V compounds, are considered inclusion of many-electron effects is shown to be fundamental in the description of excitation and ionization process. Finally, an unified picture of these impurity centers is drawn, with recourse to the crystal vacuum level.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 149
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 131-136 
    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: Most band structure calculations approximate the integral over the Brillouin zone of momentum (i.e., wave vector) dependent properties with an appropriately weighted sum over a discrete set of points in the Brillouin zone. The best choice for such a set of points has long been a point of discussion in crystalline band structure calculations. For one-dimensionally periodic systems, however, the usual choice of points has been evenly spaced points in the one-dimensional Brillouin zone with equal weights. We have analyzed the exact error for the integral over the π band of a tight-binding model of trans-polyacetylene as a function of bond alternation. We find that the error in π band energy decreases in magnitude as q-2, where q is the total number of points treated in the Brillouin zone, for the metallic polyacetylene system with equal bond lengths. As bond alternation increases, however, we find that the error in π band energy decreases in magnitude roughly exponentially as a function of bond alternation for any given value of q. We find that this systematic change in error as a function of bond alternation can lead to either apparent overestimation or underestimation of the equilibrium dimerization and stabilization energy of Peierls distorted systems using first-principles total energy calculations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 150
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 171-180 
    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 derivation and formulation of density functional theory, which eliminates the formal and practical inconsistencies and limitations of previous theories and allows its extension to stationary states other than the ground state, is given. The theory presented here can also be stated as a series of three theorems that define a family of its mathematical forms, as far as the physical content of the third theorem can either be implicitly incorporated in the density functional or explicitly in the procedure to find a solution to the equations. Examples of both cases are discussed, including the statement of configuration interaction procedure in density functional form.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 151
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 199-215 
    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 practically useful and physically realistic generalized Langevin equation of motion that governs the dynamics of a small number of chemically relevant explicit solute generalized coordinates, e.g., a reaction coordinate or a normal mode coordinate, in a molecular solvent is developed. This equation of motion, which can be made the basis of analytical treatments of spectra and rate constants in molecular solvents, naturally represents the physics of the ultrafast relaxation regime in which cage effects governed by the instantaneous cage restoring force exerted on the explicit coordinates play a dominant role. This equation of motion realistically describes both indirect (explicit coordinate → implicit coordinate → solvent) and direct (explicit coordinate → solvent) energy exchange processes as well as frequency modulation (dephasing) processes. This equation of motion also describes energy exchange with solvent vibrational as well as solvent translational-rotational degrees of freedom in a useful manner. The generalized Langevin equation for explicit coordinate motion in molecular solvents is based on the partial clamping model, which in turn assumes that (1) the liquid state motion of the explicit coordinates may be realistically approximated by small amplitude excursions from an initial point, and (2) the fluctuations in the local solvent density field are sufficiently small that the fluctuations of the perturbation density field induced by the small amplitude excursions may be ignored.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 152
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 321-339 
    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 time-dependent approach to molecular dynamics involving both electrons and nuclei is formulated to study the interaction between electronic structure and nuclear geometry during electron transfer processes. The formulation uses the time-dependent variational principle to obtain a Hamiltonian system of first-order ordinary differential equations for wave function parameters from the quantum mechanical Schrödinger equation. We apply the formulation to a two-level model. In this first application, the nuclei are treated classically. The electron transfer process in both the “normal” and the “abnormal” case is studied and discussed. The role of the nuclear motion in the electron transfer process is clearly exhibited in both two and three moiety systems. For small coupling the difference in evolution between the dynamics using adiabatic and diabatic basis states shows the importance of nuclear motion in the process. Then various aspects of applications to realistic systems are discussed, and the techniques to treat those applications are outlined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 153
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 341-354 
    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 new treatment for studying electron transfer reactions is considered. The treatment allows for a detailed description of the electronic structure and is therefore appropriate for a complete description of weakly interacting electron transfer reactions. The initial state for the electron transfer system is selected by a variational scheme. The electron transfer is pictured to take place in an encounter complex consisting of the donor, the acceptor, and (optionally) a solvent/bridge molecule. The electronic structure of the encounter complex is dynamically coupled to the surrounding solvent, and the direct time evolution of the electron transfer system is followed by a nonlinear time-dependent Hartree-Fock method. We present examples with benzeneanion radical as the donor, pyridine as the acceptor, and water as the bridge/solvent molecule. The general formalism appears to be a useful approach for studying electron transfer reactions in solution.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 154
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987) 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 155
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 697-697 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 156
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 699-705 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 157
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 469-473 
    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: Electron propagator theory is used to calculate vertical ionization energies of closed shell anions. Third order diagonal self-energies are calculated using the post-Hartree-Fock utility subroutines of GAUSSIAN 82. Higher order corrections are estimated using the outer valence approximation. The number of operations needed rises no faster than the number required for the limited two-electron integral transformation. Basis set augmentations are made until changes in the computational results are small. Adiabatic ionization energies are obtained via many body perturbation theory calculations on the neutral potential energy surface. Applications to BeH- and MgH- give results in excellent agreement with photodetachment experiments.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 158
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 513-521 
    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 symmetric group approach is presented for performing large scale, direct configuration interaction (CI) studies of electronic correlation effects in molecules. Two alternative graphical methods are described for representing very large sets of lexically ordered orbital configurations. One is suited for truncations in the number of core orbitals and the other for changes in the number of virtual orbitals. The Hamiltonian matrix elements are constructed using a graphical approach for localizing the one-and two-electron contributions. Compact and direct algorithms are given for calculating the irreducible representation matrices of S(N) for the “line-up” permutations. The program implementation of the CI procedure, PEDICI, calculates directly firstorder molecular one-electron properties and transition probabilities from a multireference space for general excitation schemes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 159
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 747-753 
    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 concept is advanced explaining how low resolution studies of chaotic spectral regions can result in assignable regular spectra. The concept draws on ideas from resonance scattering theory, and application is made to interpretation of vibrational spectra in the quasicontinuum.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 160
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 795-821 
    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 notion of resonances in different settings is discussed. Two methods for localizing the resonances in the complex plane are given and applied to model potentials.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 161
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 823-831 
    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 new implementation of the complex coordinate method for calculation of molecular resonances and photoionization cross sections is presented. The method originates from the idea of analytic continuation of stabilization graphs, but instead all matrix elements are numerically continued. Exterior scaling is invoked in conjunction with the use of dilationally adapted basis sets. It is operationally equivalent to the bivariational method in the Feshbach-partitioned manifold of complex basis functions, but no complex integrals are calculated. Instead, the complex eigenvalue problem arises from the analytical continuation of the realvalued matrix elements pertinent to any atomic or molecular structure code in its standard (real) form. That includes the possibility of using numerical basis sets. Since the method does not require modification of existing numerical codes, it can serve as a complement to any large scale CI or MCSCF molecular structure calculation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 162
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 833-840 
    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 review the main experimental results obtained in the multielectron multiphoton ionization of rare gases. Multiple ionization is interpretated as a sequential process. We study the influence of many-electron effects in multiphoton ionization within the framework of the random phase approximation. This is applied to a calculation of the two-photon ionization cross section of xenon. Finally, the role of screening effects in the multiphoton stripping of heavy atoms (Xe) is estimated.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 163
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 603-612 
    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: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 164
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 661-668 
    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 MO calculations were carried out for fluoro(porphinato)iron(III) in order to elucidate the origin of the out-of-plane displacement of the iron atom and to analyze vibrational modes of the axial ligand bond. Potential curves as functions of the Fe out-of-plane displacement and Fe—F bond distance were calculated for the ground state. By using these potential curves, the equilibrium iron displacement, Fe—F bond distance, and normal mode frequency of the Fe—F stretching vibration were evaluated. The values are in good agreement with experimental values within the differences 0.02 Å, 0.06 Å, and 50 cm-1, respectively. It has been confirmed that the Fe out-of-plane displacement is caused mainly by the Coulomb repulsion between porphine nitrogens and fluorine anion.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 165
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 699-712 
    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 connections between Jacobi matrices, continued fractions, orthogonal polynomials, three-term recurrence relationships, and the time-independent Schrödinger equation are reviewed and applied to obtain bound states and/or resonances for (1)The inverted oscillator Hamiltonian (1/2) (p2 - r2)(2)The Coulomb plus oscillator Hamiltonian p2 - zr-1 + (r + β)2/4α2(3)A general Hamiltonian P2 + V(r) in the lattice approximation with explicit examples for V(r) = -z/r or λr It is pointed out that a scattering theory follows naturally from the properties of the subdominant boundary value solution to the associated recurrence relationship. As an example we calculate the lattice Coulomb s wave phase shift.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 166
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 737-742 
    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 HeI and HeII photoelectron spectra of CF3Cl, CF3Br, CF3I, CF3CCH, CF3CCl3, CF3COOH, CF3COOCH3, CF3COOCF3, CF3COOH2COCH3, (CF3)2CHOH, CF3CH2OH, trifluoromethyltoluene, and 2, 4, 6-tris(trifluoromethyl)-1, 3, 5-triazine have been recorded under low and high resolution. Special attention has been paid to ionizations arising from MO's with a significant contribution of fluorine atomic orbitals. HeII/HeI intensity comparisons were also useful in the assignment of “CF3-group orbitals.” The results indicate that the electronic structure of the CF3 group remains rather unaffected by the rest of the molecule.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 167
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 753-754 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 168
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 763-764 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 169
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 989-989 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 170
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 975-988 
    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: Frozen-core calculations on the (He) 2s22p6 - 1S state of the F- ion and the (Ar) 3d44s2 - 5D state of the Cr atom, obtained with differently reduced basis sets and different core-projection schemes, are presented and compared with the corresponding all-electron results in order to analyze the behavior of the core projection under these circumstances. Severe truncation of the valence basis set can give frozen-core results noticeably deviated from the all electron values if the regular projection (projection factors xg = 2.0) is adopted. Much better results are obtained in these cases if a softer projection (xg = 1.0) is used for those core orbitals having high electronic density in regions where the valence basis set has low flexibility. In these circumstances the expectation value of the core projector becomes a nonvanishing correction to the valence energy because the core-valence orthogonality is incomplete after core projection.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 171
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 1-11 
    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: According to the maximum overlap method and the concept that the overlap integral may be used as an indicator of bond strength, a further discussion of bond strength F, an universal formula of F, and the correlation between the bond strength discussed here and that defined by Pauling have been given in this paper. For the type of molecule MLk, under the approximations of k = 2 and using the projection method of the angular part of bond orbitals, the same results as those derived by Pauling can be obtained from the universal formula. From the same formula, two more equations containing g and h atomic orbitals have been derived.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 172
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 31-33 
    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 “measurement” interpretation is given to the phenomenological damping terms invoked by Dunne, Stamper, and Murrell to resolve density matrices to pure states following time evolution in a nonadiabatic molecular collision.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 173
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 61-69 
    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 theoretically shown that under the influence of an appropriately directed external electric field (ε) in H2CO or a similar molecule (of the XYC = O type), the barrier to planar inversion in the 3n π* state decreases as the field strength increases. The molecule assumes a forced planar geometry in the 3n π* state rather abruptly when ε(applied) 〉 ε(critical). This phenomenon of field-induced change of structure of an isolated molecule has the attributes of a first order phase transition. The effects should be spectroscopically detectable in the inversion spectrum. The existence of another critical field strength at which the molecule makes a more or less continuous transition from the normal convalent to a purely ionic structure is demonstrated and rationalized through a simple model.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 174
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 87-104 
    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 present the freeon, singlet, unitary group formulation of many-body theory as an alternative to the particle-number-conserving, spin-projected, fermion, second-quantized formulation. It is based on the generator-state-approach (GSA) developed in part 23 of this series. We develop C1, perturbation, coupled-cluster, and random-phase theories.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 175
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 133-147 
    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 symmetry adaptation procedure of Chen et al. [Sciencia Sinica 23, 1116 (1980)], which can account for the invariance properties of the Hamiltonian with respect to any finite point group G, is both modified and adapted to the Clifford algebra unitary group approach (CAUGA). From orthogonal symmetry adapted Mo's, one first constructs a pure configuration many-electron basis adapted to the chain U(ni) ⊃ G ⊃ G(s) in terms of the U(ni) Gel'fand-Tsetlin (GT) basis, where ni is the dimension of the irrep defining a given pure configuration, and G(s) designates the canonical chain supplying a unique labeling. The pure configuration basis is then coupled to the desired G-adapted states using the point group Clebsch-Gordan coefficients and the U(n1) ⊂ U(n1 + n2) ⊂ … ⊂ U(n) basis by using the permutation group outer-product reduction coefficients. This basis can be expressed in terms of the U(n) GT basis by using the U(n) subduction coefficients (SAC'S). The SDC'S are particularly simple for the highest weight states (Hess's) of various subproblems, which can be in turn represented through the U(2n) two-box Weyl tableaux of CAUGA. The non-HWS's are obtained by applying the U(ni) lowering generators to the HWS's. In this way we can directly obtain the spin and point group adapted CAUGA basis. The procedure is illustrated on a nontrivial example.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 176
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 193-205 
    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 recently developed crystalline cluster method within the framework of the Johnson multiple scattering technique was successfully used in calculations of ionic cubic crystals and the defects with a cubic symmetry. In this paper a simple way of extension of the method to noncubic systems by a partial elimination of “muffin-tin” approximation (MTA) is proposed.The procedure suggested does reduce the intermediate integrals to the one-dimensional ones, and they are calculated analytically. It is supposed that an approach of taking into account the nonspherical shape of the potential inside the “muffin-tin” (MT) spheres will be effective in crystals with an ionic type of chemical bond.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 177
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 265-277 
    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 semiempirical MO method SINDO1 is extended to second-row atoms from sodium to chlorine. The basis set has a provision to include d orbitals. To retain rotational invariance in a d orbital set, a number of hybrid integrals has to be included that invalidate the zero differential overlap (ZDO) assumption even in a symmetrically orthogonalized basis set. The inclusion of d orbitals rendered the set-up of integral calculation of the original INDO method impractical. Instead of one subroutine for each integral, all explicitly calculated integrals (overlap, core, electronic repulsion) are now contained in a single subroutine under unifying aspects. The parametrization scheme includes pseudopotentials and adjusts the total energy under inclusion of zero point energies to experimental heats of formation of ground states. The vibrational frequencies for the calculation of zero point energies are obtained from calculated force constants and G matrix elements by a scaling procedure. The results for geometries, energies, and dipole moments are compared with MNDO data.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 178
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 349-359 
    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 very simple derivation of the Coulomb Green's function in IR3 is presented, which is based on an application of the Kustaanheimo-Stiefel transformation directly to the equation defining the harmonic oscillator Green's function in IR4. The representation that we obtain makes it possible to Fourier transform the Green's function with respect to its space variables by means of a simple Gaussian integration. The method that we use can readily be applied to several other Hamiltonians.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 179
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 595-612 
    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: Conformational studies on some p-dimethylamino β-aza and β-aza (with respect to the dimethylamino phenyl ring) styryl dyes derived from quinoline-4, quinoline-2, pyridine-4, pyridine-2, and benzothiazole-2 have been carried out using the quantum mechanical PCILO (perturbative configuration interaction using localized orbitals) method. These molecules may be considered as heterocyclic analogues of benzylidene anilines whose conformations have been studied extensively by both theoretical and experimental methods to explain the difference of their spectra from the isoelectronic benzylidene compounds. The results of the present studies show that the β-aza styryl dyes are nearly planar. In case of β-aza styryl dyes, although the phenyl ring is coplanar with the central atoms, there is a substantial twist of the heterocyclic ring. These results are explained in terms of CT-1 and CT-2 effects and are used as a possible explanation for the observed spectral and sensitization properties.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 180
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 669-683 
    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: Investigations of general properties of time evolution of both classical and quantum systems show that the evolution (on a microscopic level) is reversible, and, if there is an approach to equilibrium, it exists only in the sense of weak convergence and necessarily in both directions of time. In this connection attempts to derive irreversibility and the approach to equilibrium in the sense of strong convergence and without any loss of information (using the so-called Lyapunov converters) are discussed. After demonstrating their drawbacks, an alternative approach is proposed based on the spectral properties of the generator of the group. The relevant spectral criteria for the approach of both classical and quantum ensembles to equilibrium are given, and the decisive role of loss of information in obtaining stronger variants of convergence is emphasized. The asymmetry between initial and any other state  - consisting of different levels of information needed to prepare the states - is proposed as an adequate explanation of irreversibility. The importance of the method of complex scaling in this context is discussed, and its application in proving some spectral properties in the quantal Hamiltonian formulation is stressed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 181
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987) 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 182
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 45-53 
    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 present for the first time a calculation of the one-electron excitations of gallium arsenide that explicitely accounts for the exchange nonlocality. The calculation has been performed in two steps: (1) An exact valence electron Hartree-Fock computation provides a self-consistent one-body density matrix and defines the one electron valence and conduction wave functions subspaces. (2) An effective Hamiltonian including screened exchange is constructed and diagonalized after projection onto the valence and the conduction subspaces separately. This leads to self-consistent dispersion curves that compare favorably with experimental data.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 183
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 79-87 
    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 consider the dielectric response to an acceptor ion placed at the center of a GaAs quantum well of finite depth and calculate the binding energy of heavy-hole and light-hole acceptor atoms as a function of the width of the well. We compare our values with those we have calculated from a hydrogenic approximation and find that consideration of the dielectric response of the GaAs quantum well leads to deviations with respect to the hydrogenic approximation. Specifically, we find that our binding energies are larger in magnitude than those calculated from the hydrogenic approximation. We further find that the acceptor ion binding a heavy hole is much more affected by the dielectric response of the GaAs quantum well than the acceptor ion that binds a light hole.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 184
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 105-113 
    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 self-consistent formulation of the variational cellular method has been developed in order to calculate the electronic structure of crystals with an arbitrary number of atoms per unit cell. Applications for silicon have been carried out. Silicon, chosen here as a test case, is treated as a face-centered cubic lattice with four “atoms” per unit cell by adding empty cells. The electronic charge density was taken muffin-tin, assuming a constant value in the interstitial region between the inscribed sphere and the Wigner-Seitz polyhedrum. The spherical symmetric electronic charge density in the inscribed sphere was obtained by adding a limited number of contributions of Brillouin zone states using the “mean value point theory” developed by Baldereschi and Chadi-Cohen. Our results are in good agreement with those obtained by other methods.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 185
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 153-162 
    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 molecular conformations of four three-phenyl oligomers of polyaniline are determined via a CNDO/S3 molecular orbital analysis of optical absorption and valenceelectron photoemission spectra for fully hydrogenated (“Leucoemeraldine”: N-4-aminophenyl-N′-phenyl-1, 4 diaminobenzene and N-phenyl-N′-phenyl-1, 4 diaminobenzene), partially hydrogenated (“emeraldine”: N-4-aminophenyl-N′-phenyl- 1, 4-diiminobenzene), and fully oxidized (“pernigraniline”: N-phenyl-N′-phenyl- 1, 4-diiminobenzene) species. The results provide a quantitative description of the optical absorption and photoemission data.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 186
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 217-227 
    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: Self-consistent field (SCF) wave functions for CO2 are used to calculate cross sections for the elastic and inelastic scattering of fast electrons and x-rays from CO2 molecules. The effects of basis set choice and free rotation on these cross sections are investigated. The utility of an approximate scheme to correct SCF inelastic cross sections for the effects of electron correlation is examined. The probability density for the interelectronic distance, or radial intracule density, is obtained as a by-product.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 187
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 245-249 
    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 survey of recent developments in the theory and experimental knowledge of charged interfaces is discussed in relation to the problem of electron transfer reactions. An attempt is made to reformulate the role of the solvent in bulk phase and at surfaces. Furthermore we discuss the effect of position-dependent tunneling on the reaction rate constant assuming simple distribution of the ions near the metallic interface.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 188
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 297-306 
    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 calculations of single and double differential cross sections for ionization by fast, charged particles within the framework of Born approximation are presented. In addition, a semiempirical method based on the asymptotic Bethe-Born expansion is also discussed. Both are applied to ionization of helium by electrons and protons in an effort to assess their accuracy and validity. Agreement with experiment is quite good. The implications for other targets is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 189
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 363-375 
    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 review is given of some applications of a novel form of self-energy theory. These include the image force experienced by an electron near a metal, the van der Waals interaction between two molecules, and the polarization potential of atomic scattering theory.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 190
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 407-415 
    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: Our procedure for employing analytical gradients of ab initio potential energy hypersurfaces in the description of centrifugally distorted molecules is applied to an asymmetric top, namely water. Both single determinantal (HF/6-31G**) and configuration-interaction (CISD/6-31G**) surfaces were utilized. Quartic centrifugal spectroscopic coefficients are obtained in both cases and are in reasonable agreement with experiment. It is shown that the calculated dependence of the energy upon the rotational angular momentum is better represented by a Padé approximant than by the conventional power series.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 191
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 457-468 
    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: With this work, we begin our treatment of the transition metal electron affinities. A procedure, REDUCE, for reducing the number of parental couplings per configuration present in the first order wave function from as many as 100 to only a few is introduced. Progress toward a comprehensive relativistic-correlation theory is discussed. Several states in Sc- were examined but none were found to be bound. Two new bound states were obtained for Cu-: 3d9 4s 4p2 5D and 3d8 4s 4P3 7F0, with electron affinities 0.109 and 1.052 eV, respectively.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 192
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 487-493 
    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: Analytical derivatives are dependent upon derivatives of the Ao basis set and the MO relaxation. By separating these effects on derivatives, they can be individually studied. We show that the coupled-cluster single and double (CCSD) model introduces most of the MO relaxation effects required by gradients, hessians, dipole, and polarizability derivatives. This finding should make it possible to simplify analytical derivative evaluation at the CCSD level.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 193
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 523-532 
    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: Basis set “balance” in the expansion of the large and small components of Dirac 4-spinors has proved successful in preventing the blatant “variational failure” that has plagued Dirac-Fock basis set expansion calculations. The criterion of basis set balance, however, was derived from the Dirac equation assuming that the external Coulomb potential V satisfies the condition |V| ≪ c2. Consequently, for a finite value of c, a conventional balanced basis does not necessarily satisfy the boundary condition at the origin, although it may recover the correct nonrelativistic limit as c approaches infinity. This is the case with “balanced” Gaussian basis calculations that employ the point nucleus approximation. We show that this drawback may be removed by forfeiting the point nucleus approximation in favor of a finite nucleus of uniform proton charge distribution: the imposition of the finite nucleus boundary causes the solution to be Gaussian at the origin.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 194
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 32 (1987), S. 555-562 
    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: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 195
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 3-16 
    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: Based upon the invariance of N-particle systems under discrete operations of reflection, inversion, and rotation by 2π/n, a method for obtaining complete sets of relations among energy derivatives of all orders has been presented. The method is based on the criterion that, for a discrete symmetry operation such as reflection across a plane; the change in energy due to simultaneous arbitrary displacements of each particle is equal to another set of “conjugate” displacements of all particles. Applications of the above relations for particular molecular systems possessing a combination of symmetry operations is also presented. Here, via the row echelon analysis, the number of independent derivatives are found, and simple symmetry relations that allow determination of the remaining derivatives are presented. For example, for a homonuclear diatomic molecule with D2h symmetry only 1 of the 6 first derivatives and 1 of the 21 second derivatives need to be independently calculated.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 196
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 57-63 
    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 quasiclassical trajectory surface hopping method has been used to study H2+(v) + H2 → H3+ + H for v = 0, 3, 7, 10, 13, and 17 with an emphasis on determining the H3+ internal energy and angular momentum distributions for high v. For v = 13 and 17, significant cross sections are found for producing H3+ at energies above its dissociation energy. An average metastable H3+ lifetime of 11.5 ps for v = 13 and 4.7 ps for v = 17 is found, but there is also a much longer lived component to the lifetime distributions that is more important for v = 13 than for v = 17. Some of the longer lived metastables correspond to high angular momentum orbiting states of H3+, but other sources of metastability are also present.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 197
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 91-97 
    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 electronic structure aspects of the quenching reaction Li(2P) + HCl → LiCl + H were studied using ab initio state averaged multiconfiguration self consistent field/configuration interaction methods. This reaction proceeds through an avoided crossing of the 1, 2 2A' potential energy surfaces. A region of strong electronic nonadiabaticity was located and (first derivative) nonadiabatic coupling strengths computed. This region of strong electronic nonadiabaticity occurs near a (local) minimum on the 2 2A' potential energy surface which is exoergic relative to its reactant asymptote, Li(2P) + HCl.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 198
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 133-159 
    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 microscopic, state-to-state reaction dynamics of charge transfer reactions are reviewed for the two system N2+(N2, N2)N2+ and Ar+(N2, Ar)N2+. The crossed molecular beam method demonstrates that the symmetric, molecular case proceeds by two mechanisms at low collision energy (〈 0.7 eV). One of these involves an orbiting complex in which the total available energy is redistributed, essentially statistically. The second mechanism is a direct mechanism which involves nearly rectilinear trajectories and corresponds to exactly resonant charge transfer at low energy (0.7 eV) and charge transfer accompanied by vibrational excitation at higher energy (〉 10 eV). The orbiting mechanism is dominant at low energies and disappears entirely with increasing collision energy. The unsymmetric, nearly resonant charge transfer reaction is direct at all energies. At very low collision energy (0.6 eV) and moderate collision energy (〉 1.5 eV) the dominant reaction channel is the generation of N2+(X2 g, v = 1) with little rotational excitation. At 0.6 eV substantial angular scattering (including back-scattering) is observed; above 1.5 eV the trajectories are essentially rectilinear. At intermediate energies (0.8 〈 E 〈 1.3 eV) a very different mechanism is observed. All the energetically accessible vibrational states of N2+ are formed, each with a preferred scattering angle at a given energy. Related experiments and theoretical models which rationalize some, but not all, of these results are described. The most intriguing puzzle is the “energy window” in which quantum-state specific, angular-specific reactive scattering is observed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 199
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 179-184 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 200
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 31 (1987), S. 161-172 
    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: This work describes a novel trochoidal electron spectrometer and illustrates its properties on a few examples. In the first example vibrational excitation in the small molecules H2 and N2 is measured. Comparison of the results with theoretical work points to the neccessity of using non local methods for correct treatment of near-threshold region and of extremely short-lived resonances. In the second example the observation of resonant autodetachment of Feshbach resonances in many organic molecules is reported.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...