Analysis of cooperativity and localization for atomic rearrangements

TL;DR

This paper introduces new measures for analyzing atomic rearrangements, revealing that cooperative rearrangements generally have lower energy barriers and that sampling methods influence the types of rearrangements observed.

Contribution

It presents novel measures of localization and cooperativity and analyzes how different sampling techniques bias the observed atomic rearrangements.

Findings

Cooperative rearrangements have lower barriers than uncooperative ones.

Sampling methods influence the observed types of rearrangements.

Linear interpolation favors cooperative rearrangements.

Abstract

We propose new measures of localization and cooperativity for the analysis of atomic rearrangements. We show that for both clusters and bulk material cooperative rearrangements usually have significantly lower barriers than uncooperative ones, irrespective of the degree of localization. We also find that previous methods used to sample stationary points are biased towards rearrangements of particular types. Linear interpolation between local minima in double-ended transition state searches tends to produce cooperative rearrangements, while random perturbations of all the coordinates, as sometimes used in single-ended searches, has the opposite effect.