Quantum chemical calculations of coupled vibrations of adsorbates: A comparative study of CO/Cu(1Â 1Â 0) and O/diamond (1Â 0Â 0)

We have performed quantum chemical calculations for coupled oscillations examining CO adsorbed on Cu(1 1 0) and atomic oxygen on the (1 0 0) diamond face. For CO, we find that our calculations show coupling consistent with a dynamic dipole-dipole interaction. In the case of the adsorbed oxygen atoms the dominant coupling seems to be mechanical. The limits of the semiempirical method SAM1 are tested for consistency and precision. Our model gives accuracy within 10% when compared to experiment and works well with near neighbor adsorbates.