Close-coupling wave packet approach to numerically exact molecule–surface scattering calculations

In this paper we describe the theory and application of the recently developed close-coupling wave packet (CCWP) method to the study of transition probabilities of H2 scattered from flat and corrugated surfaces. We present an improved method of analyzing the final wave function which permits S matrices and transition probabilities to be obtained over a wide range of energies from the propagation of a single wave packet. Transition probabilities obtained using the CCWP method are in excellent agreement with those obtained from time-independent close-coupling (CC) calculations. For the present three-dimensional H2-corrugated surface scattering study, the CCWP calculations require roughly one-tenth of the computation time of the CC method. Our results indicate that the CCWP method should be a very efficient method of obtaining highly accurate scattering results both for standard collision problems and for collision problems which cannot be readily treated using standard CC methods.