Two-bath model for activated surface diffusion of interacting adsorbates

TL;DR

This paper introduces a two-bath stochastic model to describe the diffusion of adsorbates on surfaces, accounting for thermal phonons and collisions, and applies it to sodium atoms on copper surfaces.

Contribution

It presents a novel two-bath model extending the Caldeira-Leggett framework to better simulate adsorbate diffusion on surfaces.

Findings

Effective description of adsorbate diffusion at low coverages

Model captures effects of surface phonons and collisions separately

Application to Na on Cu(001) demonstrates model's utility

Abstract

The diffusion and low vibrational motions of adsorbates on surfaces can be well described by a purely stochastic model, the so-called interacting single adsorbate model, for low-moderate coverages (\theta \lesssim 0.12). Within this model, the effects of thermal surface phonons and adsorbate-adsorbate collisions are accounted for by two uncorrelated noise functions which arise in a natural way from a two-bath model based on a generalization of the one-bath Caldeira-Leggett Hamiltonian. As an illustration, the model is applied to the diffusion of Na atoms on a Cu(001) surface with different coverages.