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1

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Analysis of the IGLO bond contributions to the 13C shielding tensors in the local bond frame (1987)

Facelli, Julio C. ; Grant, David M. ; Michl, Josef

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 31 (1987), S. 45-55

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ISSN: 0020-7608

Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A 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

URL: http://dx.doi.org/10.1002/qua.560310106

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Cubic-grid Gaussian basis sets for electron scattering calculations. II. Matrix elements (1995)

Čársky, Petr ; Hrouda, Vojtěch ; Michl, Josef

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 53 (1995), S. 431-436

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ISSN: 0020-7608

Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: In this article, we report an efficient computational procedure for electron scattering matrix elements in the previously developed cubic-grid Gaussian basis sets. The Green function matrix elements derived for the cubic-grid basis set are simpler and easier to calculate than are those available in the literature for conventional Gaussian basis sets. Special features of the cubic-grid basis sets may also be exploited for a very efficient computation of Coulomb and exchange integrals. Inelastic scattering amplitudes for vibrational excitations may be efficiently calcualted in the harmonic approximation by numerical differention of the T-matrix elements. © 1995 John Wiley & Sons, Inc.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/qua.560530409

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Cubic-grid Gaussian basis sets for electron scattering calculations. III. Effect of basis-set translation and size on the calculated cross section (1995)

Čársky, Petr ; Hrouda, Vojtěch ; Michl, Josef ; [et al.]

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 53 (1995), S. 437-450

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ISSN: 0020-7608

Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Previously developed cubic-grid basis sets of various sizes were used for the calculation of cross sections for elastic and inelastic electron scattering by the He and Ne atoms and the H2O molecule by the T-matrix expansion method. The aim was to test the invariance of calculated cross sections with respect to the translation of the target molecule and to examine the effect of basis-set size on the results. We also present a simple procedure for accounting for long-range interactions from the part of space that lies outside the volume that contains the cubic-grid basis set. © 1995 John Wiley & Sons, Inc.

Additional Material: 11 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/qua.560530410

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Ag vibrational levels of cyclobutadiene on a new potential energy surface (1991)

Čársky, Petr ; Downing, John W. ; Michl, Josef

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 40 (1991), S. 415-420

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ISSN: 0020-7608

Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: GVB/[5s3p1d/3s1p] energies were calculated for 31 geometries of cyclobutadiene in the D2h point group. These geometries differed in the values of the symmetrized internal coordinates for two CC stretching and one CCH bending modes. The data points were fitted to the expansions of in powers of . Variational calculations provided the following energies of the lowest Ag vibrational levels (with respect to the vibrational ground state): 4.4; 1161.2; 1162.3; 1304.0; 1322.8; 1920.3; and 1991.0 cm-1.

Additional Material: 3 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/qua.560400313

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Cubic-grid Gaussian basis sets for electron scattering calculations. I. Definition and construction (1995)

Čársky, Petr ; Hrouda, Vojtéch ; Michl, Josef

New York, NY : Wiley-Blackwell

International Journal of Quantum Chemistry 53 (1995), S. 419-429

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ISSN: 0020-7608

Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: We propose a new type of Gaussian basis sets for use in calculations of electron scattering by molecules. Instead of locating the basis-set functions on the atomic centers of the target molecule, we place primitive s-type Gaussians at the positions of a cubic lattice with a regular grid. The grid and the Gaussian exponent are fixed so as to give the best representation of the plane-wave function. Plane-wave functions and Green functions obtained by means of the cubic-grid basis set are tested graphically against exact functions and functions expressed by means of a conventional Gaussian basis set. © 1995 John Wiley & Sons, Inc.

Additional Material: 9 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/qua.560530408

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Triazoles. XIVFor Part XIII, see Ref. 1. - 15N NMR study of substituted 5-amino-1,2,4-triazolesPresented in part at the Annual Conferenc of the Hungarian Chemical Society, Debrecen, Hungary, 1987, and at the 9th Symposium on the Chemistry of Heterocyclic Compounds, Bratislava, Czechoslovakia, 1987. (1989)

Orendt, Anita M. ; Michl, Josef ; Reiter, József

Chichester : Wiley-Blackwell

Organic Magnetic Resonance 27 (1989), S. 1-3

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ISSN: 0749-1581

Keywords: 15N NMR ; 5-Amino-1,2,4-triazoles ; Tautomerism ; Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: 15N NMR chemical shifts were measured for a series of substituted 5-amino-1,2,4-triazoles. The assignment of isomeric structures agrees with earlier results obtained with the use of proton-coupled 13C NMR.

Additional Material: 1 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/mrc.1260270102

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An SCF study of 10-vertex and 12-vertex boranes and heteroboranesThis work was supported by the National Science Foundation (INT 8903188). We wish to thank Dr. P.v.R. Schleyer for providing us a preprint of reference 17. We thank the University of Texas at Austin for a grant of computer time. (1991)

Zahradník, Rudolf ; Balaji, V. ; Michl, Josef

New York, NY [u.a.] : Wiley-Blackwell

Journal of Computational Chemistry 12 (1991), S. 1147-1156

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ISSN: 0192-8651

Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Computer Science

Notes: For symmetry-constrained boranes B10H102-, B12H122-, and their valence isoelectronic analogues containing a single hetero atom, completely optimized geometries were obtained using Hartree-Fock SCF calculations with the 3-21G and 6-31G* basis sets. For the anionic and dianionic species, the geometry optimization was also carried out using the 6-31 + G* basis set. Harmonic vibrational frequencies were obtained at HF/3-21G level. The results compare well with experiment where available.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcc.540120914

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