Relativistic electronic structure calculation of selected diatomic and triatomic molecules using effective core potentials

Abstract

Kramers`` restricted Hartree-Fock (KRHF) calculations using relativistic effective core potentials have been performed for the ground state configuration of diatomic molecules (PbO, SnO, GeO, PbS, SnS, GeS, $Bi_2$, $Sb_2$, $As_2$) and triatomic molecules ($PoH_2$, $TeH_2$, $SH_2$, $OH-2$). Equilibrium geometries, harmonic frequencies, Mulliken population analysis, molecular spinor energies, and atomic spinor energies are evaluated. Particular attention has been given to an understanding of relativistic effects (especially spin-orbit effects). Molecular spin-orbit corrections appear to be essential to some molecules including heavy atom. Direct inversion in the iterative subspace (DIIS) method has been applied to this program and help the convergency.