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Half‐projected and projected Hartree‐Fock calculations for singlet ground states. II. Lithium hydride
Author(s) -
Smeyers Yves G.,
DelgadoBarrio G.
Publication year - 1974
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.560080508
Subject(s) - lithium hydride , singlet state , hartree–fock method , dipole , chemistry , lithium (medication) , ground state , eigenvalues and eigenvectors , spin (aerodynamics) , binding energy , slater determinant , atomic physics , physics , computational chemistry , quantum mechanics , thermodynamics , ion , atomic orbital , excited state , medicine , organic chemistry , ionic bonding , endocrinology , electron
Abstract The half‐projected Hartree–Fock function ( HPHF ) for singlet states is defined as a linear combination of two Slater determinants which contains only spin eigenstates with even spin quantum numbers. The possible uses of such an approach for determining molecular properties are investigated computing the potential energy curve, binding energy, force constant, and dipole moment variation corresponding to the lithium hydride ground state. Full projected and restricted Hartree–Fock calculations ( PHF and RHF ) are performed simultaneously for comparison purposes. It is found that the HPHF model yields very satisfactory results, very close to those of the PHF scheme. Both models predict properly the molecular behavior as a function of nuclear separation, whereas the RHF one fails. A discussion is given in terms of configuration equivalents. It is concluded that the HPHF scheme seems to be useful for determining molecular properties specially in the case of large systems in which the more sophisticated methods are unmanageable.