Numerical methods for the parametrization of the lattice generalized langevin equation: applications to surface desoprtion.

The effect of phonons on a single site within a harmonic lattice may be studied using the generalized Langevin equation (GLE), wherein phononic fluctuations are represented by non-Markovian stochastic force and friction terms. The simplicity of the lattice GLE approach has made it a popular choice in applications to the study of surface-gas interactions. However, the determination of the functional form of the friction kernel, and it's role the desoprtion process, remain open challenges. Here we present numerical methods for the calculation of the friction kernel using data taken from molecular dynamics (MD) simulations. Our methods are advantageous in that they may be applied to study the effects of heterogenities, such as surface clusters or defects, as well as the effects of solvents. Results are shown for homogenuous Pt(III) surfaces of various sizes, in vacuum and in water, as well as Au nanoclusters. Finally, we benchmark the GLE models against atomistic MD simulations in the calculation of surface desoprtion rates.