VIBRATIONAL-SPECTRUM OF (CO)(2) ON CU(100) - QUANTUM CALCULATIONS WITH 18 COUPLED MODES

We report calculations of the vibrational frequencies of CO dimer on C u(100) using the recently developed vibrational self-consistent field code. Eighteen modes are treated explicitly within a three-mode repres entation of the potential. Nine symmetry-distinct doublets are observe d and the corresponding frequencies are computed. The thermally broade ned spectrum of the GO-stretch fundamental is calculated at various te mperatures. Both the temperature and coverage dependence of both the a verage GO-stretch frequency and the corresponding linewidth are consis tent with experimentally observed trends. (C) 1998 American Institute of Physics. [S0021-9606(98)70141-2].