Premium
Lower bound molecular orbitals for H 2 + , HeH ++ , and H 3 ++
Author(s) -
Johnson J. W.,
Poshusta R. D.
Publication year - 1977
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.560110515
Subject(s) - molecular orbital , sto ng basis sets , slater type orbital , atomic orbital , molecular orbital theory , atomic physics , gaussian , linear combination of atomic orbitals , upper and lower bounds , localized molecular orbitals , chemistry , physics , computational chemistry , molecule , quantum mechanics , mathematics , electron , mathematical analysis
Gaussian orbitals are used to calculate Temple lower bounds for H 2 + , HeH ++ , and H 3 ++ . Molecular orbitals are constructed from individual Gaussian‐type orbitals ( GTO ) and from GTO contractions adapted for either upper or lower bounds of the hydrogen atoms. The MOS are optimized by minimizing either the upper bound, 〈H〉, or the variance, 〈( H – E ) 2 〉. The best Temple lower bounds achieved by these methods are −0.60336 a.u. for 2 + , − 1.06224 a.u. for HeH ++ , and −0.13003 a.u. for H 3 ++ . Comparison is made with other types of molecular orbitals and with the exact wave functions for 2 + , HeH ++ . Analysis of the nuclear cusps is given. A prescription for constructing lower bound molecular orbitals is offered.