scholarly journals Converged Hartree-Fock and electron correlation calculations using systematically constructed basis sets of primitive Gaussian type functions of s-symmetry

1996 ◽  
Vol 1 (1) ◽  
pp. 93-102 ◽  
Author(s):  
A. S. Shalabi
Keyword(s):  
Electron Correlation ◽  
Basis Sets ◽  
Hartree Fock ◽  
Gaussian Type

An approximate ab initio method based on the DIM model

2000 ◽  
Vol 78 (12) ◽  
pp. 1575-1586 ◽  
Author(s):  
John M Cullen
Keyword(s):  
Ab Initio ◽  
Excited States ◽  
Electron Correlation ◽  
Correlation Energy ◽  
Basis Sets ◽  
Ab Initio Method ◽  
First Order ◽  
Hartree Fock ◽  
Modified Method ◽  
Electron Correlation Energy

Using a second quantized formulation, an approximate diatomics in molecules (DIM) theory is presented in which all three- and four-centered electronic integrals are neglected. To ameliorate the effects of this approximation, the DIM one electron operator is constructed so that the true ab initio first-order density matrix and total energy are reproduced at the Hartree–Fock level. The resulting model was extensively tested for a variety of basis sets for its capability of capturing both the dynamic and nondynamic components of the electron correlation energy as well as the energies of excited electronic states. A modified method in which the DIM one-electron operator is formed from the initial extended Hückel guess of the Hartree–Fock orbitals was also found to produce excellent results.Key words: DIM, electron correlation energy, excited states, semiempirical.

scholarly journals THE INTERACTION OF Co2+-AMMONIA MODELLING: THE COMPARATIVE STUDY BETWEEN AB INITIO AND ELECTRON CORRELATION METHODS

2010 ◽  
Vol 2 (2) ◽  
pp. 67-73
Author(s):  
Harno Dwi Pranowo ◽  
Foliatini Foliatini ◽  
Karna Wijaya
Keyword(s):  
Charge Transfer ◽  
Comparative Study ◽  
Electron Correlation ◽  
Transfer Effect ◽  
Basis Set ◽  
Basis Sets ◽  
Complex Energy ◽  
Hartree Fock ◽  
Correlation Methods ◽  
The Comparative Study

Research on comparison between Hartree-Fock method and electron correlation methods as well as the effect of size of basis sets on representing interaction of Co2+-NH3 observed from complex energy parameters and optimum geometric parameters have been carried out.The first step is screening basis sets based on charge transfer effect and BSSE value. The selected basis set does not yield charge transfer at 1,4 Å  

On the performance of molecular model core potential orbitals in spin-orbit and electron correlation studies

1996 ◽  
Vol 74 (6) ◽  
pp. 1248-1252 ◽  
Author(s):  
Dietmar Krause ◽  
Mariusz Klobukowski
Keyword(s):  
Electron Correlation ◽  
Correlation Energy ◽  
Molecular Model ◽  
Virtual Space ◽  
Coupling Constants ◽  
Basis Sets ◽  
Spin Orbit ◽  
Hartree Fock ◽  
Electron Correlation Effects ◽  
Model Core Potentials

The role of improved parametrization and accurate basis sets in model core potentials was studied in calculations of the spin-orbit coupling constants (in PH, AsH, and SbH) and of the electron correlation effects (in P2, As2, and Sb2). An effective method of identifying and removing the intruder quasi-core orbitals from the virtual orbital space was proposed in connection with the post-Hartree–Fock calculations. The results demonstrated that (a) the flexible valence basis sets allow evaluation of the spin-orbit effects without resorting to any scaling techniques and (b) the intruder quasi-core orbitals, even if left imbedded in the virtual space, have negligible effect on the values of the electron correlation energy. Key words: effective core potentials, basis sets, spin-orbit effects, electron correlation.

Double even tempering of orbital exponents: Application to Roothaan-Hartree-Fock calculations for He through Xe in Slater-type basis sets

1994 ◽  
Vol 88 (4) ◽  
pp. 273-283 ◽  
Author(s):  
Toshikatsu Koga ◽  
Hiroshi Tatewaki ◽  
Ajit J. Thakkar
Keyword(s):  
Basis Sets ◽  
Slater Type ◽  
Hartree Fock ◽  
Orbital Exponents

Basis sets for ab initio periodic Hartree?Fock studies of zeolite/adsorbate interactions: He, Ne, and Ar in silica sodalite

1996 ◽  
Vol 60 (4) ◽  
pp. 809-820 ◽  
Author(s):  
Roberto Nada ◽  
John B. Nicholas ◽  
Maureen I. McCarthy ◽  
Anthony C. Hess
Keyword(s):  
Ab Initio ◽  
Basis Sets ◽  
Hartree Fock

Gaussian basis sets by generator coordinate Hartree–Fock method to ab initio calculations of electron affinities of enolates

2002 ◽  
Vol 587 (1-3) ◽  
pp. 9-17 ◽  
Author(s):  
R.M.L Savedra ◽  
J.C Pinheiro ◽  
O Treu Filho ◽  
R.T Kondo
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Basis Sets ◽  
Electron Affinities ◽  
Gaussian Basis Sets ◽  
Hartree Fock ◽  
Generator Coordinate

Improvements in Algorithms for Two Electron Repulsion Integrals Evaluation in Gaussian Type Basis Sets

2007 ◽  
Author(s):  
Marcin Makowski ◽  
Theodore E. Simos ◽  
George Maroulis
Keyword(s):  
Basis Sets ◽  
Gaussian Type ◽  
Electron Repulsion ◽  
Electron Repulsion Integrals
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