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Explicitly correlated SCF study of small hydrides
Author(s) -
Shillady Donald D.,
Craig John,
Rutan Sarah
Publication year - 2001
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.1511
Subject(s) - atomic orbital , solvation , quantum monte carlo , coulomb , gaussian , electronic correlation , chemistry , hartree–fock method , scaling , statistical physics , monte carlo method , quantum mechanics , physics , electron , atomic physics , computational chemistry , molecule , mathematics , statistics , geometry
The “soft Coulomb hole” method of Chakravorty and Clementi has been implemented in a Gaussian lobe‐orbital (GLO) program to include explicit electron–electron correlation in molecules according to a modified form of Coulomb's law in a program for workstations and personal computers (PCLOBE):f ( R 12 )=(1−exp (− w ( R 12 ) 2 ))/ R 12 , w =scaling parameter. Twice as many two‐electron integrals must be calculated compared to the usual Hartree–Fock–Roothaan algorithm, but this “correlated self‐consistent field (SCF)” method may be embedded within well‐known SCF computer codes and yields more than 90% of the correlation energy in run times less than twice that of the restricted Hartree–Fock (RHF) method. A two‐parameter model of correlation is calibrated on HF and LiH using the 6‐311G** basis as Gaussian lobe orbitals. The quantum Monte Carlo energies of LiH and HF were fitted to within 150 cal/mol, but the scaling model for first‐row atoms is less good for H 2 . This work shows promise as a fast way to modify the Hartree–Fock–Roothaan method for accuracy approaching quantum Monte Carlo methods. This proof‐of‐concept work offers extension to modeling solvation properties of water solutions in high‐pressure liquid chromatography (HPLC). © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001