DISSOCIATIVE CHEMISORPTION OF CH4 ON NI - THE ROLE OF MOLECULAR-ORIENTATION

The dissociation of CH4 on a Ni surface is examined quantum mechanical ly. The molecule is treated as a quasidiatomic R-H, where R=CH3, and v ibrational, rotational, and translational motion normal to the surface are included. The metal surface is assumed to be flat and the potenti al energy surface is based on ab initio studies of dissociation over t he Ni(111) atop site. Lattice motion is introduced via the surface mas s model. Bessel-Legendre and fast Fourier transform pseudospectral tec hniques are used to evolve the wave function in time, and energy resol ved reactive fluxes are extracted via a time-to-energy transform. Agre ement with experiment is good, particularly with regard to the depende nce of the dissociation probability on incident energy and surface tem perature. The dynamics of the dissociation reaction for the various in itial states of the molecule are examined. (C) 1998 American Institute of Physics.