Lower bound molecular orbitals for H, HeH++, and H

Abstract
Gaussian orbitals are used to calculate Temple lower bounds for H, HeH++, and H. 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, 〈(HE)2〉. The best Temple lower bounds achieved by these methods are −0.60336 a.u. for , − 1.06224 a.u. for HeH++, and −0.13003 a.u. for H. Comparison is made with other types of molecular orbitals and with the exact wave functions for , HeH++. Analysis of the nuclear cusps is given. A prescription for constructing lower bound molecular orbitals is offered.

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