Four-dimensional quantum and two-dimensional classical mechanical study ofmolecule-surface interactions

The collision of a hydrogen molecule with a copper surface has been studied using a semiclassical theory. The four molecular coordinates, the distance from the surface, the vibrational coordinate, and the polar angles, are tr eated quantum mechanically using a grid method. The kinetic energy is evalu ated by a fast Fourier transformation (FFT) technique and the wave function propagated by a Lanczos iterative method. Two translational degrees of fre edom for motion at the lattice are treated classically, whereas the normal modes of the solid are quantized using a quantum boson approach. The presen t calculation indicates that rotational state distributions of the scattere d molecule and dissociative chemisorption of the diatom on the metal surfac e are significantly affected by the phonon coupling. (C) 2000 American Inst itute of Physics. [S0021-9606(00)70207-8].