A Systematic abinitio LCAO–MO–SCF Study of the Ionization Potentials, Electron, Proton, Hydrogen, and Hydride Affinities of SHn Molecules and Ions

Equilibrium geometries and energies are obtained for SHn (n = 0, 1, 2, 3) neutral and charged species by the Roothaan LCAO–MO–SCF method. A large gaussian basis set including d and p polarization functions was employed. The calculated ionization potentials, electron, proton, hydrogen, and hydride affinities are discussed as well as compared with similar previously calculated properties for OHn (n = 0, 1, 2, 3) species.

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LCAO—MO–SCF Calculations on LiH Using Gaussian Basis Set

The Journal of Chemical Physics ◽

10.1063/1.1726952 ◽

1966 ◽

Vol 44 (5) ◽

pp. 1849-1855 ◽

Cited By ~ 26

Author(s):

I. G. Csizmadia

Keyword(s):

Basis Set ◽

Gaussian Basis Set ◽

Scf Calculations ◽

Lcao Mo

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A Comprehensive Computational Study on OCH+-Rg (Rg = He, Ne, Ar, Kr, Xe) Complexes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20030489 ◽

2003 ◽

Vol 68 (3) ◽

pp. 489-508 ◽

Cited By ~ 2

Author(s):

Yinghong Sheng ◽

Jerzy Leszczynski

Keyword(s):

Computational Study ◽

Relativistic Effects ◽

Dft Method ◽

Basis Set ◽

Rare Gas ◽

Geometrical Parameters ◽

Minor Effect ◽

Dissociation Energies ◽

Equilibrium Geometries

The equilibrium geometries, harmonic vibrational frenquencies, and the dissociation energies of the OCH+-Rg (Rg = He, Ne, Ar, Kr, and Xe) complexes were calculated at the DFT, MP2, MP4, CCSD, and CCSD(T) levels of theory. In the lighter OCH+-Rg (Rg = He, Ne, Ar) rare gas complexes, the DFT and MP4 methods tend to produce longer Rg-H+ distance than the CCSD(T) level value, and the CCSD-calculated Rg-H+ bond lengths are slightly shorter. DFT method is not reliable to study weak interaction in the OCH+-He and OCH+-Ne complexes. A qualitative result can be obtained for OCH+-Ar complex by using the DFT method; however, a higher-level method using a larger basis set is required for the quantitative predictions. For heavier atom (Kr, Xe)-containing complexes, only the CCSD method predicted longer Rg-H+ distance than that obtained at the CCSD(T) level. The DFT method can be applied to obtain the semiquantitative results. The relativistic effects are expected to have minor effect on the geometrical parameters, the H+-C stretching mode, and the dissociation energy. However, the dissociation energies are sensitive to the quality of the basis set. The nature of interaction between the OCH+ ion and Rg atoms was also analyzed in terms of the interaction energy components.

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Basis set dependence of SO stretching frequencies and its consequences for IR and VCD spectra predictions

Physical Chemistry Chemical Physics ◽

10.1039/d0cp05420h ◽

2020 ◽

Vol 22 (48) ◽

pp. 27979-27986

Author(s):

Kevin Scholten ◽

Elric Engelage ◽

Christian Merten

Keyword(s):

Ir Spectra ◽

Model Systems ◽

Basis Set ◽

Polarization Functions

Using chiral tosylates as model systems we evaluate the effect of diffuse and polarization functions on the quality of predicted VCD and IR spectra. Polarization functions on sulfur are shown to be important to reliable determine ACs using VCD.

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Formulation of theLCAS MS SCF method within the Gaussian basis set

International Journal of Quantum Chemistry ◽

10.1002/qua.560180112 ◽

1980 ◽

Vol 18 (1) ◽

pp. 65-71 ◽

Cited By ~ 1

Author(s):

Szczepan Roszak ◽

Henryk Chojnacki

Keyword(s):

Basis Set ◽

Gaussian Basis Set

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Topological Effect on MO Energies, IX. On Topologically Related 1,4-Dibora-2,3-diazarine and 1,4-Dibora-2,5-diazarine

Zeitschrift für Naturforschung B ◽

10.1515/znb-1984-0812 ◽

1984 ◽

Vol 39 (8) ◽

pp. 1053-1057 ◽

Cited By ~ 5

Author(s):

loan Motoc ◽

Oskar E. Polansky

Keyword(s):

Basis Set ◽

Complete Agreement ◽

Mo Calculations ◽

Symmetry Constraint ◽

Topological Effect ◽

Equilibrium Geometries

AbstractMinimal STO-NG (N = 3, 4 and 6 ) basis set non-empirical HF SCF MO calculations have been performed for topologically related 1,4-dibora-2,3-diazarine (S) and 1,4-dibora-2,5-diazarine (T). The equilibrium geometries of these S and T isomers have been computed by symmetry-constraint geometry optimizations using the STO-3G basis set. The calculations lead to the prediction that: i) the T isomer is about 48 kJ/mole less stable than the S isomer, and ii) the π -MO energy patterns of the S and T isomers are in complete agreement with the TEMO theorem, while the bonding σ-MO eigenvalues exhibit four inversion points.

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Comparison of the Conformational Stability for Several Vinylhalomethanes and Silanes with Experiment Using MP2 Perturbation Theory and DFT

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20070015 ◽

2007 ◽

Vol 72 (1) ◽

pp. 15-50 ◽

Cited By ~ 3

Author(s):

Wolfgang Förner ◽

Hassan M. Badawi

Keyword(s):

Experimental Data ◽

Vibrational Spectra ◽

Recent Literature ◽

Conformational Stability ◽

Basis Set ◽

Major Conclusion ◽

Stable Conformer ◽

Polarization Functions ◽

Complete Series ◽

Triple Zeta

In recent literature it was reported that the valence triple zeta basis set augmented by polarization functions is not too reliable for vinyl monohalo- and dihalomethanes and -silanes, the halogen being fluorine and chlorine. The major conclusion was that a valence triple zeta basis is too small to be augmented by polarization functions in a balanced way, at least on vinylmonofluoromethane. Thus we decided to apply the 6-311++G** basis set to the complete series of methanes, silanes and germanes (the latter ones are just added for completeness because no experimental data are available for them and, moreover, we published them already previously) and to compare the results to experimental data available in the literature to see whether the failures of this basis set show up in the complete series of molecules. In the literature we found five such molecules and the information which of the conformers is the most stable. Indeed we found that predictions on the relative stability of conformers in those systems with this basis set and MP2 as well as DFT are with a 60:40 chance, three being correct predictions and two being incorrect ones out of the five. However, since the energy differences are rather small in these systems and due to the fact that - as a consequence of twofold degeneracy of the gauche conformer on the potential curve of the torsional vibration - the abundances of the conformers in equilibrium do not change too much, we decided to calculate also vibrational spectra for three examples and to compare them also to experiment. It is reported that besides the failures in total energy (we have chosen two examples where predictions of the nature of the stable conformer are correct, and one where it is not), the vibrational spectra are rather well reproduced, especially when experimental energies are used to calculate abundances in equilibrium in the case where the prediction of the stable conformer failed.

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