Exact classical simulation of hydrogen migration on Ni(100): The role of fluctuations, recrossing, and multiple jumps

Abstract

We examine the migration of a classical hydrogen atom adsorbed on a Ni(100) surface, in a temperature range when the motion consists of jumps between lattice sites. We view these jumps as isomerization reactions and calculate exactly their rate constants by using the correlation function theory. We examine in detail the effect of lattice motion, lattice fluctuations and lattice distortion on the jumping rates and test the accuracy of the transition state theory. We propose a new approximation to the rate constant which includes all the effects incorporated in the transition state theory and calculates approximately the dynamic correction due to recrossing. We find that the magnitude of the diffusion coefficient is affected by multiple jumps.