Surface diffusion and low vibrational motion with interacting adsorbates: A shot noise description

TL;DR

This paper introduces a shot noise-based approach to model surface diffusion and vibrational motion of interacting adsorbates, simplifying analysis and aligning well with experimental data.

Contribution

It proposes the interacting single adsorbate approximation, a stochastic model that captures complex surface dynamics efficiently and accurately.

Findings

Model reproduces quasielastic peak broadening observed experimentally

Approach simplifies understanding of surface diffusion dynamics

Less computationally demanding than molecular dynamics simulations

Abstract

Here, an approach in terms of shot noise is proposed to study and characterize surface diffusion and low vibrational motion when having interacting adsorbates on surfaces. In what we call statistical limit, that is, at long times and high number of collisions, one expects that diffusing particles display an essential Markovian behavior. Accordingly, the action of the pairwise potentials accounting for particle-particle collisions is equivalent to considering a shot noise acting on a single particle. We call this approach the interacting single adsorbate approximation, which gathers three important advantages: (i) the dynamics underlying surface diffusion and low vibrational motion can be easily understood in terms of relatively simple stochastic processes; (ii) from our model, appropriate (and well justified) working formulas are easily obtained, which explain the results arising from more complicated (but commonly used) molecular dynamics simulations within the Langevin formulation; and (iii), at the same time, it is less demanding computationally than the latter type of calculations. In order to illustrate the application of this model, numerical results are presented. Specially, our model reproduces the experimental observation regarding the broadening of the quasielastic peak ruling surface diffusion.