Semiempirical Molecular Orbitals for General Polyatomic Molecules. II. One-Electron Model Prediction of the H–O–H Angle

A consistent one‐electron semiempirical molecular orbital method based on the approximation $$H_{\mathrm{ij}}{\mathrm{=S}}_{\mathrm{ij}}{\text{(2−|\hspace{0.17em}S}}_{\mathrm{ij}}{\mathrm{\hspace{0.17em}|)(H}}_{\mathrm{ii}}{\mathrm{+H}}_{\mathrm{jj}}\text{)/2}$$ has been used with atomic data to predict the equilibrium geometry of the water molecule. A variety of plausible parameters predict an equilibrium H–O–H angle in the range 95°—105°. Success and limitations of the method are attributed to the fidelity with which it reproduces important one‐electron effects. In less critical cases, this model resembles the Wolfsberg—Helmholz and other non‐Hückel semiempirical MO treatments.