On the use of spatial symmetry in ab initio calculations. Transformation of the two-electron integrals from atomic orbital to localized molecular orbital basis

1993 ◽  
Vol 13 (1) ◽  
pp. 107-113
Author(s):  
Ede Kapuy ◽  
Cornelia Kozmutza
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Atomic Orbital ◽  
Spatial Symmetry ◽  
Orbital Basis

Tetrafluorocyclodisilazanes: synthesis, crystal structure, and molecular orbital ab initio calculations

1995 ◽  
Vol 494 (1-2) ◽  
pp. 133-142 ◽  
Author(s):  
Thomas Müller ◽  
Yitzhak Apeloig ◽  
Ina Hemme ◽  
Uwe Klingebiel ◽  
Mathias Noltemeyer
Keyword(s):  
Crystal Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Orbital

CNDO/2 Calculations for Organohalides

1986 ◽  
Vol 39 (2) ◽  
pp. 233 ◽  
Author(s):  
TH Spurling ◽  
DA Winkler
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Organic Molecules ◽  
Molecular Orbital Calculations ◽  
Semiempirical Molecular Orbital

A CNDO/2 parameterization for performing semiempirical molecular orbital calculations for organic molecules containing bromine and iodine is presented; the results are superior to those from other parameterizations, and generally agree with ab initio calculations and experiment.

scholarly journals The Structures, Molecular Orbital Properties and Vibrational Spectra of the Homo- and Heterodimers of Sulphur Dioxide and Ozone. An Ab Initio Study

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 626
Author(s):  
Thomas A. Ford
Keyword(s):  
Experimental Data ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Vibrational Spectra ◽  
Sulphur Dioxide ◽  
Higher Order ◽  
Adduct Formation ◽  
Molecular Orbitals ◽  
Ab Initio Study

The structures of a number of dimers of sulphur dioxide and ozone were optimized by means of a series of ab initio calculations. The dimer species were classified as either genuine energy minima or transition states of first or higher order, and the most probable structures consistent with the experimental data were confirmed. The molecular orbitals engaged in the interactions resulting in adduct formation were identified and relations between the orbitals of the dimers of the valence isoelectronic monomer species were examined. The vibrational spectra of the most probable structures were computed and compared with those reported in the literature, particularly with spectra observed in cryogenic matrices. The calculations were extended to predict the properties of a number of possible heterodimers formed between sulphur dioxide and ozone.

Structures, Energies, Torsional Barriers, and Vibrational Spectra of Three Rotamers of Tetrasulfane, H2S4

1995 ◽  
Vol 50 (6) ◽  
pp. 889-893 ◽  
Author(s):  
Yana Drozdova ◽  
Karol Miaskiewicz ◽  
Ralf Steudel
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Transition States ◽  
Infrared And Raman Spectra ◽  
Lone Pairs ◽  
Central Bond ◽  
Vibrational Wavenumbers

Ab initio calculations at the MP2/6-311 G **//MP2/6-311 G** level show that the all-trans, cis-trans and all-cis rotamers of H2S4 are practically of identical energy. Their vibrational wavenumbers are also practically identical and in agreement with the observed infrared and Raman spectra of dissolved H2S4. On rotation about the central bond of H2S4 the torsional barriers are found to be 32.0 (cis -barrier) and 26.6 kJ mol-1 (trans-barrier). The geometries of the two transition states with τSSSS = 0° and 180° can be explained by hyperconjugation between the lone pairs at the terminal sulfur atoms and the σ * molecular orbital of the central bond.

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