Stochastic models for surface diffusion of molecules
Abstract
We derive a stochastic model for the surface diffusion of molecules, starting from the classical equations of motion for an N-atom molecule on a surface. The equation of motion becomes a generalized Langevin equation for the center of mass of the molecule, with a non-Markovian friction kernel. In the Markov approximation, a standard Langevin equation is recovered, and the effect of the molecular vibrations on the diffusion is seen to lead to an increase in the friction for center of mass motion. This effective friction has a simple form that depends on the curvature of the lowest energy diffusion path in the 3N-dimensional coordinate space. We also find that so long as the intramolecular forces are sufficiently strong, memory effects are usually not significant and the Markov approximation can be employed, resulting in a simple one-dimensional model that can account for the effect of the dynamics of the molecular vibrations on the diffusive motion.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 28, 2014
- Source ID
- 10.1063/1.4890661
Entities
People
- Hans Jürgen Kreuzer
- Patrick Shea
Organizations
- Dalhousie University
- Office of Naval Research