Cubic force constants and equilibrium geometry of methane from Hartree–Fock and correlated wavefunctions

1978 ◽  
Vol 68 (11) ◽  
pp. 5077-5085 ◽  
Author(s):  
Péter Pulay ◽  
Wilfried Meyer ◽  
James E. Boggs
Keyword(s):  
Force Constants ◽  
Equilibrium Geometry ◽  
Hartree Fock

An ab initio Calculation of the Force Constants, Vibrational Frequencies, and Equilibrium Geometry of HCP

1975 ◽  
Vol 30 (8) ◽  
pp. 1015-1017 ◽  
Author(s):  
P. Botschwina ◽  
K. Pecul ◽  
H. Preuss
Keyword(s):  
Ab Initio ◽  
Ab Initio Calculation ◽  
Relaxation Method ◽  
Force Constants ◽  
Equilibrium Geometry ◽  
Harmonic Force ◽  
Hartree Fock ◽  
Force Method ◽  
Force Relaxation ◽  
Good Agreement

Abstract All the harmonic, the diagonal cubic and quartic stretching and the semidiagonal cubic force constants of HCP have been calculated from Hartree-Fock wavefunctions by the force method of Pulay. The force constants are in good agreement with the experimental ones, except for FRR, Faa, FRr, FRaa, and Fraa the latter two being rather uncertain from experiment. From the harmonic force constants, harmonic frequencies have been calculated by the method of Wilson and Eliashevich. The equilibrium geometry of HCP has been calculated by the force relaxation method of Pulay.

Ab initio Hartree-Fock treatment of ionic and semi-ionic compounds: state of the art

1992 ◽  
Vol 341 (1661) ◽  
pp. 203-210 ◽  
Keyword(s):  
Ab Initio ◽  
State Of The Art ◽  
Basis Set ◽  
Equilibrium Geometry ◽  
Mulliken Population ◽  
Atomic Orbitals ◽  
Oxygen Ions ◽  
Hartree Fock ◽  
Ionic Compounds ◽  
Mn Oxides

The periodic ab initio Hartree-Fock approach is applied to the Li, Na, K, Be, Mg, Ca and Mn oxides, and to Al 2 O 3 (corundum) and SiO 2 (a-quartz). A local basis set (‘atomic orbitals’) is used. The equilibrium geometry, the formation energy and the bulk modulus are calculated, with reasonable agreement with experiment. The influence of the environment on the oxygen ions is discussed through the Mulliken population and band structure data.

Hartree–Fock calculation for the electronic structure of H+3 using numerically optimized orbitals

2001 ◽  
Vol 79 (2-3) ◽  
pp. 673-679
Author(s):  
J D Talman
Keyword(s):  
Electronic Structure ◽  
Ground State ◽  
Equilateral Triangle ◽  
Wave Functions ◽  
Equilibrium Geometry ◽  
Molecular Ion ◽  
Interatomic Spacing ◽  
Hartree Fock ◽  
Gaussian Orbitals

The Hartree–Fock wave functions for the ground state of the H2 molecule and the H+3 molecular ion are computed using radial orbitals that are numerically optimized. It is shown that these orbitals yield results comparable in accuracy to those obtained using much larger bases of Gaussian orbitals. As in previous calculations, the equilibrium geometry for H+3 is found to be that of an equilateral triangle, with an interatomic spacing of 1.64a0. PACS No.: 13.15+q

Analytic force constants for post‐Hartree–Fock wave functions: The simplest case

1983 ◽  
Vol 78 (3) ◽  
pp. 1607-1608 ◽  
Author(s):  
Yukio Yamaguchi ◽  
Yoshihiro Osamura ◽  
George Fitzgerald ◽  
Henry F. Schaefer
Keyword(s):  
Wave Functions ◽  
Force Constants ◽  
Hartree Fock

AbInitio Computation of Force Constants. II. The Estimation of Dissociation Energies from abinitio SCF Calculations

1975 ◽  
Vol 53 (23) ◽  
pp. 3599-3601 ◽  
Author(s):  
H. Bernhard Schlegel ◽  
Saul Wolfe ◽  
Fernando Bernardi
Keyword(s):  
Morse Potential ◽  
Force Constants ◽  
Hartree Fock ◽  
Dissociation Energies ◽  
Scf Calculations

The dissociation energies of second and third period hydrides have been estimated by fitting a Morse potential to the harmonic and cubic stretching force constants computed from abinitio wavefunctions. The estimates thus obtained are superior to dissociation energies computed by direct differences of Hartree–Fock energies.

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