Rate theory for correlated processes: Double-jumps in adatom diffusion

TL;DR

This paper develops a transition path theory to analyze correlated double-jumps in adatom diffusion on platinum surfaces, providing explicit calculations and revealing a sqrt{T} prefactor due to a cusp in the acceptance region.

Contribution

It introduces a new theoretical framework for understanding correlated multi-barrier activated processes and explicitly calculates the minimum-energy trajectory for double-jumps.

Findings

Activation energy determined by minimum-energy trajectory.

Explicit calculation of double-jump trajectories.

Rate exhibits a sqrt{T} temperature dependence.

Abstract

We study the rate of activated motion over multiple barriers, in particular the correlated double-jump of an adatom diffusing on a missing-row reconstructed Platinum (110) surface. We develop a Transition Path Theory, showing that the activation energy is given by the minimum-energy trajectory which succeeds in the double-jump. We explicitly calculate this trajectory within an effective-medium molecular dynamics simulation. A cusp in the acceptance region leads to a sqrt{T} prefactor for the activated rate of double-jumps. Theory and numerical results agree.