Implementation of distortion symmetry for the nudged elastic band method with DiSPy

Abstract

The nudged elastic band (NEB) method is a commonly used approach for the calculation of minimum energy pathways of kinetic processes. However, the final paths obtained rely heavily on the nature of the initially chosen path. This often necessitates running multiple calculations with differing starting points in order to obtain accurate results. Recently, it has been shown that the NEB algorithm can only conserve or raise the distortion symmetry exhibited by an initial pathway. Using this knowledge, symmetry-adapted perturbations can be generated and used as a tool to systematically lower the initial path symmetry, enabling the exploration of other low-energy pathways that may exist. The group and representation theory details behind this process are presented and implemented in a standalone piece of software (DiSPy). The method is then demonstrated by applying it to the calculation of ferroelectric switching pathways in LiNbO3. Previously reported pathways are more easily obtained, with new paths also being found which involve a higher degree of atomic coordination.

Suppressing the ferroelectric switching barrier in hybrid improper ferroelectrics

“…Distortion symmetry groups 44,58 are used to enumerate and name the possible initial pathways following ref. 22 with the help of the DiSPy package 59 . All the switching pathways reported in the text retain their symmetry for all values of the reaction coordinate under NEB calculation.…”

Suppressing The Ferroelectric Switching Barrier in Hybrid Improper Ferroelectrics

“…Distortion symmetry groups [48,61] are used to enumerate and name the possible initial pathways following Ref. [22] with the help of the DiSPy package [62]. All the switching pathways reported in the text retain their symmetry for all values of the reaction coordinate under NEB calculation.…”