Tests of approximations for inelastic molecule–surface scattering dynamics

• Published in: The Journal of chemical physics Vol. 86; no. 9; pp. 4885 - 4894
• Main Authors: Diestler, Dennis J., Riley, Merle E.
• Format: Journal Article
• Language: English
• Published: Woodbury, NY American Institute of Physics 01.05.1987
• Subjects: Atomic and molecular collision processes and interactions; Atomic and molecular physics; Exact sciences and technology; Other topics in atomic and molecular collision processes and interactions; Physics; Molecule surface collision; Cubic crystals; Inelastic scattering; Sticking coefficient; Atom surface collision; Theoretical study; Classical theory; Morse model; Comparative study; Truncation
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.452659

Any classical dynamical simulation of atom– or molecule–surface scattering is subject to the approximation of truncating the many-body description of the solid to that of a tractable number of atoms (the P zone). This truncation should have no significant effect on the collision dynamics, e.g., the accommodation coefficients and sticking probabilities, for the situation of interest. No ab initio tests of the accuracy of the few existing approximate treatments of gas–surface scattering appear to have been reported. In this work we review the existing approximations and introduce three new ones. One of the three new ones, the weak-coupling approximation, assumes the solid atoms tend to respond independently to the incident molecule; another, the bond-corrected Debye approximation, is a simple modification of the Adelman–Doll damping theory; the third, the outgoing wave approximation, treats the solid as an elastic continuum, in which the wave-like disturbance created by the collision is propagated outwardly from an epicenter near the point of impact. In all, six different approximations are applied to a collision system (adatom interacting via a Morse potential with the simple-cubic Rosenstock–Newell lattice at 0 K) for which numerically exact scattering data (energy accommodation coefficients) are available. Figures of merit are assigned to each approximation over a wide range of collisional parameters. The new outgoing wave approximation is consistently of the highest quality. The results are very encouraging for the easy application of reliable approximations to P zones with only a few atoms