Semiempirical Molecular Orbital Calculations. I. The Electronic Structure of H2O and H2S

The results of calculations of the molecular orbitals of H₂S and H₂O are reported. The molecular orbital energies were obtained at the self‐consistent charge distribution, from the secular equation $${\mathrm{|H}}_{\mathrm{ij}}{\mathrm{-EG}}_{\mathrm{ij}}\text{|=0.}$$ An open‐shell treatment of the oxygen and sulfur p orbitals was used, together with the relationship, $H_{\mathrm{ij}}{\text{=(2−| S}}_{\mathrm{ij}}{\mathrm{|\; )(H}}_{\mathrm{ii}}{\mathrm{+H}}_{\mathrm{jj}}{\mathrm{)G}}_{\mathrm{ij}}\text{/2}$ for the resonance integrals. The orbital energies agree very well with those from ab initio calculations and the method should prove useful with larger molecules where a more sophisticated treatment is not feasible.