Diffusion of atoms interacting by long-range and oscillating forces

TL;DR

This paper calculates the collective diffusion coefficient of a one-dimensional lattice gas with long-range and oscillating interactions, revealing oscillatory behavior influenced by substrate lattice and interaction length.

Contribution

It introduces a variational approach to analyze how long-range and oscillating inter-particle forces affect diffusion in lattice gases.

Findings

Diffusion coefficient varies strongly with adsorbate density.

Oscillations in diffusion coefficient depend on interaction length and lattice structure.

Interplay between inter-particle distances and substrate lattice causes oscillatory diffusion behavior.

Abstract

Collective diffusion coefficient in a one dimensional lattice gas adsorbate is calculated using variational approach. Particles interact via either a long-range, or a long range electron-gas-mediated (for a metallic substrate), or a Lennard-Jones interaction. Diffusion coefficient as a function of the adsorbate density strongly depends on the relationship between the substrate lattice constant and the characteristic length of the inter--particle interaction potential (which determines positions of the potential energy minima). The diffusion coefficient at fixed density as a function of the interaction characteristic length has an oscillating character due to the interplay between the inter--particle distances allowed by the substrate lattice structure and the average inter--particle distances which minimize the total interaction energy.