Theoretical predictions of the molecular structure of sulphur tetrafluoride

1975 ◽  
Vol 28 (9) ◽  
pp. 2069 ◽  
Author(s):  
L Radom ◽  
III HF Schaefer
Keyword(s):  
Basis Set ◽  
Basis Sets ◽  
Structure Theory ◽  
Equilibrium Geometry ◽  
Double Zeta ◽  
Theoretical Predictions ◽  
Self Consistent Field ◽  
Polarization Functions ◽  
Hypervalent Molecules ◽  
Scf Calculations

The equilibrium geometry of the SF4 molecule has been investigated by means of ab initio electronic structure theory. Self-consistent-field (SCF) calculations employing a minimum basis set (MBS) incorrectly predict SF4 to have a square- pyramidal (C4V) structure. The correct qualitative prediction of a C2V geometry is obtained with a basis of nearly double zeta quality. Comparable calculations on H2S and SF2 suggest that it may only be for hypervalent molecules containing sulphur that minimum basis sets are inappropriate. However, polarization functions seem to be necessary for an accurate prediction of S-F bond distances.

Orbital exponent optimization for molecular self-consistent-field wave functions including the polarization function

1992 ◽  
Vol 70 (2) ◽  
pp. 547-554 ◽  
Author(s):  
Kenro Hashimoto ◽  
Yoshihiro Osamura
Keyword(s):  
Wave Functions ◽  
Basis Set ◽  
Polarization Function ◽  
Orbital Exponent ◽  
Consistent Field ◽  
Energy Gradient ◽  
Double Zeta ◽  
Self Consistent Field ◽  
Polarization Functions ◽  
Field Wave

We have applied the analytical energy gradient method with respect to the orbital exponents for molecular self-consistent-field wave functions including the polarization functions. The gradients for Gaussian-type functions in Huzinaga–Dunning's double zeta basis set with and without polarization functions were compared for some hydrides of the first-row elements. The changes in the gradients caused by the polarization functions were observed. It was found that the polarization functions on hydrogen play a role in reducing the gradients produced in the absence of these functions. Although optimization of the exponents gives results depending on the molecules, the total energies as well as the dipole moments are insensitive to the exponent values. We could confirm that the exponents for Gaussian functions in the standard double zeta plus polarization basis set work adequately by coupling with the variational parameters for the simple hydrides even if they have gradients in the molecules. Keywords: orbital exponent, Gaussian-type functions, analytical energy gradient, molecular SCF wave function, polarization function.

scholarly journals Comprehensive Basis-Set Testing of Extended Symmetry-Adapted Perturbation Theory and Assessment of Mixed-Basis Combinations to Reduce Cost

2021 ◽  
Author(s):  
Montgomery Gray ◽  
John Herbert
Keyword(s):  
Perturbation Theory ◽  
Significant Loss ◽  
Basis Set ◽  
Basis Sets ◽  
Many Body ◽  
Hartree Fock ◽  
Double Zeta ◽  
Polarization Functions ◽  
Correlation Consistent ◽  
Consistent Basis

Hybrid or "extended" symmetry-adapted perturbation theory (XSAPT) replaces traditional SAPT's treatment of dispersion with better-performing alternatives, while at the same time extending two-body (dimer) SAPT to a many-body treatment of polarization using a self-consistent charge-embedding procedure. The present work presents a systematic study of how XSAPT interaction energies and energy components converge with respect to the choice of Gaussian basis set. Although errors can be reduced in a systematic way using correlation-consistent basis sets, similar performance at lower cost is obtained using Karlsruhe basis sets, and we introduce new versions with limited augmentation (diffuse functions) that are even more efficient. Pople-style basis sets, which are even more efficient, often afford good results if a large number of polarization functions are included. The dispersion models used in XSAPT afford much faster basis-set convergence as compared to the perturbative description of dispersion in conventional SAPT, meaning that "compromise" basis sets (such as jun-cc-pVDZ) are no longer required and benchmark-quality results can be obtained using basis sets of triple-zeta quality. The use of diffuse functions proves to be essential, especially for the description of hydrogen bonds. The "delta(Hartree-Fock)" correction that accounts for high-order induction can be performed in double-zeta basis sets without significant loss of accuracy, leading to a mixed-basis approach that offers 4x speedup over the existing (cubic-scaling) XSAPT approach.

scholarly journals Full CI Extrapolation: Application to H2O with a Double Zeta Basis Set

1986 ◽  
Vol 39 (5) ◽  
pp. 711 ◽  
Author(s):  
PD Gray ◽  
PG Burton
Keyword(s):  
Field Configuration ◽  
Basis Set ◽  
Equilibrium Geometry ◽  
Extrapolation Procedure ◽  
Consistent Field ◽  
Double Zeta ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Full Ci ◽  
Double Zeta Basis

A previously reported full CI (configuration interaction) extrapolation procedure based on multireference single and double CI, which gave excellent results for H20 at the equilibrium geometry, is extended to two other geometries for which explicit full CI results are known. The technique is shown to provide good results for cases where the SCF (self-consistent field) configuration is not strongly dominant, although degradation of performance is noticeable in these cases. The technique is also used to predict a full CI result for the 21 Al state of H20 with the double zeta basis.

Ab Initio Calculations of the Molecular Structures and the Electronic Properties of Phospha-AlkynesR-C≡P(R=H,CH3,NH2,OH, F and Cl)

1984 ◽  
Vol 39 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Minh Tho Nguyen
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electronic Properties ◽  
Molecular Structures ◽  
Basis Sets ◽  
Effect Of Substituents ◽  
Force Method ◽  
Double Zeta ◽  
Polarization Functions ◽  
Scf Calculations

Results of ab initio SCF calculations on phospha-alkynes R-C≡P with R=H. CH3, NH2, OH. F and Cl are reported. The geometries were optimized by the force method with analytical gradient employing double zeta (DZ) basis sets. Various molecular and one-electron properties are calculated with double zeta plus polarization functions (DZ + P) and compared with experimental ones. The effect of substituents is analysed in terms of computed properties.

Universal Gaussian basis functions in relativistic quantum chemistry: atomic Dirac–Fock–Coulomb and Dirac–Fock–Breit calculations

1992 ◽  
Vol 70 (6) ◽  
pp. 1822-1826 ◽  
Author(s):  
G. L. Malli ◽  
A. B. F. Da Silva ◽  
Yasuyuki Ishikawa
Keyword(s):  
Relativistic Quantum ◽  
Basis Set ◽  
Basis Sets ◽  
Interaction Energies ◽  
Gaussian Basis Sets ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Gaussian Basis Set ◽  
Good Agreement

Matrix Dirac–Fock–Coulomb and Dirac–Fock–Breit self-consistent field calculations are performed for a number of neutral atoms. He (Z = 2) through Xe (Z = 54), using the universal Gaussian basis set (18s, 12p, 11d) reported recently by Da Silva etal. The total Dirac–Fock–Coulomb, the Dirac–Fock–Breit, and the Breit interaction energies calculated with this universal Gaussian basis set are in good agreement with the corresponding values obtained by using an extensive well-tempered Gaussian basis set for the He through Ca (Z = 20) atoms. Although this universal Gaussian basis set is inadequate for the calculation of total Dirac–Fock–Coulomb and Dirac–Fock–Breit energies for the Kr, Sr, and Xe atoms, the Breit interaction energies calculated with this basis for these three atoms are in very good agreement with the corresponding Breit interaction energies obtained by using the extensive well-tempered Gaussian basis sets. Work is in progress to generate a more extensive and energetically better universal Gaussian basis set for He through Xe for its use in non-relativistic Hartree–Fock as well as Dirac–Fock self-consistent field calculations on polyatomics involving heavy atoms.

A comparative theoretical study of the electronic structure of some nickel(II) azides, thiocyanates, and isothiocyanates

1998 ◽  
Vol 76 (7) ◽  
pp. 1006-1014 ◽  
Author(s):  
R H Abu-Eittah ◽  
M El-Esawy ◽  
N Ghoneim ◽  
A T Aly
Keyword(s):  
Electronic Structure ◽  
Electronic Structures ◽  
Theoretical Study ◽  
Molecular Orbitals ◽  
Basis Sets ◽  
Theoretical Treatment ◽  
Double Zeta ◽  
Experimental Values ◽  
Scf Calculations ◽  
Split Valence

The electronic structure, conformation, and molecular orbitals of some nickel(II) azides, thiocyanates, and isothiocyanates have been studied. Three different basis sets: split valence (SV), split valence with six d-Gaussians (SV6D), and double zeta (DZ) sets, were used to find the best ground state for nickel. It has been found that the combination, DZ-3F, gives results closest to the experimental values. The electronic structures of the nickel azides studied were completely different from those of the nickel thiocyanates. On the other hand, the electronic structures of the nickel thiocyanates studied were highly comparable to those of the corresponding nickel isothiocyanates. Molecular orbitals were computed for the complexes studied and the types of electronic transitions expected were identified and discussed.Key words: Ni(II) azides, thiocyanates, and isothiocyanates: ab initio SCF calculations; MO calculations on some Ni(II) complexes; theoretical treatment of some Ni(II) ions and salts; geometry and energetics of some nickel(II) azides, thiocyanates, and isothiocyanates.

Ab Initio Calculations of the Molecular Structures and the Electronic Properties of Sulfur-containing Compounds: III. Thioacrolein (CH2=CH–CH=S) and Thioglyoxal (S = CH–CH=S)

1982 ◽  
Vol 37 (2) ◽  
pp. 125-128
Author(s):  
Tae-Kyu Ha ◽  
M. T. Nguyen ◽  
L. Vanquickenborne
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electronic Properties ◽  
Gradient Method ◽  
Molecular Structures ◽  
Basis Set ◽  
Double Zeta ◽  
Scf Calculations ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

Abstract Results of ab initio SCF calculations on thioacrolein (CH2=CH-CH=S) and thioglyoxal (S=CH-CH=S) are reported. The geometries are optimized by the analytical gradient method using the double zeta (DZ) basis set. The trans conformers of these molecules are calculated to be more stable than the cis conformer by 2.06 and 4.31 kcal/mol, respectively.

Accurate evaluation of SCF and MP2 components of interaction energies. Complexes of HF, OH2, and NH3 with Li+

1988 ◽  
Vol 53 (10) ◽  
pp. 2214-2229 ◽  
Author(s):  
Małgorzata M. Szczęśniak ◽  
Steve Scheiner
Keyword(s):  
Point Charge ◽  
Basis Set ◽  
Basis Sets ◽  
Interaction Energies ◽  
Multipole Moments ◽  
Gaussian Basis Sets ◽  
Basis Set Superposition Error ◽  
Polarization Functions ◽  
Selection Of ◽  
Correlation Corrections

High-quality Gaussian basis sets of the well-tempered type, containing three sets of polarization functions on all atoms, are used to investigate the interaction of Li+ with HF, OH2, and NH3. These sets reproduce the SCF and MP2 energies of the various monomers very well and, moreover, accurately treat the multipole moments and polarizabilities of the monomers. When applied to the complexes, the sets are essentially free of primary and secondary basis set superposition error at the SCF level; MP2 extension effects are also completely negligible while basis set superposition effects are small but non-negligible. Analysis of the correlation corrections to the molecular properties, coupled with comparison of the interaction of the bases with a point charge, provides a straightforward explanation of correlation contributions to the interaction energy. Recommendations are provided to guide selection of basis sets for molecular interactions so as to avoid distortion of the various components.

The effect of p, d, and f Gaussian polarization functions on the computed one-electron properties of AHn oxygen and sulfur hydrides

1978 ◽  
Vol 56 (4) ◽  
pp. 543-551 ◽  
Author(s):  
Raymond Poirier ◽  
Roy Kari
Keyword(s):  
Basis Sets ◽  
Gaussian Type ◽  
Field Gradients ◽  
Isoelectronic Series ◽  
Monotonic Convergence ◽  
Polarization Functions ◽  
Scf Calculations ◽  
Made In ◽  
Lcao Mo

A series of LCAO-MO-SCF calculations, using various basis sets of Gaussian-type functions, has been made in order to study the effects of p, d, and f polarization functions on calculated one-electron properties for a 10-electron isoelectronic series of oxygen hydrides and for an 18-electron series of sulfur hydrides. Conclusions from these results suggest that several one-electron properties have a predictable, although not monotonic convergence pattern. Except for calculated field gradients, f GPF's have only a small effect on the calculated values.

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