Molecular dynamics simulations of energy flow at a solid surface. New methods using a small number of atoms

Abstract

We present a number of new methods for the treatment of the dynamics of a strongly perturbed, finite sized, anharmonic system embedded in a structured, infinite system. All of the methods divide the full system in three classes of particles: Those that are treated by molecular dynamics; those that obey some form of stochastic molecular dynamics; and, those that are fixed. The methods are all simpler than the well-known generalized Langevin equation technique, and can be applied easily to much more complex processes than is possible for the GLE. A detailed illustration is provided of the energy flow through a solid lattice following a sudden disturbance of one surface atom. We compare the different methods and establish the size of the region of moving atoms needed to describe the lattice response over various time scales for the different dynamical methods.