Abstract
Complete sets of harmonic and cubic force constants of water, methanol and silanol are calculated by the ab initio SCF method using double zeta plus polarization type basis sets. Nuclear motion corrections to equilibrium geometries are derived. The OH bonds become longer by about 1·7 pm and the XOH angles wider by about 0·15°. Vibrationally averaged r α and r g structures are calculated which agree with observed data within experimental limits of uncertainty.