Molecular-orbital-self-consistent-field cluster model ofH2O adsorption on copper

The interaction of ${\mathrm{H}}_2$O with a Cu(100) surface is modeled via cluster calculations using the self-consistent-field–linear-combination-of-atomic-orbitals–X α method. In the equilibrium on-top configuration bonding is through the oxygen with the molecular plane tilted from the normal by 70°. Bonding involves the ${\mathrm{H}}_2$O lone-pair orbitals and a charge donation to the metal. The calculated normal mode vibrational and low-frequency hindered molecular rotational frequencies agree with recent data.