A modified nudged elastic band algorithm with adaptive spring lengths

TL;DR

This paper introduces a modified NEB algorithm with adaptive spring lengths, improving the resolution around saddle points without extra computational cost or parameters, demonstrated on molecular systems.

Contribution

A novel NEB variant replaces the harmonic energy with Onsager-Machlup action, enabling adaptive resolution near saddle points.

Findings

Automatic increase in path resolution around saddle points.

Same computational cost as standard NEB.

Successful applications to molecular isomerization and defect healing.

Abstract

We present a modified version of the nudged elastic band (NEB) algorithm to find minimum energy paths con-necting two known configurations. We show that replacing the harmonic band-energy term with a discretized version of the Onsager-Machlup action leads to a NEB algorithm with adaptive spring lengths that automatically increase the resolution of the minimum energy path around the saddle point of the potential energy surface. The method has the same computational cost per optimization step of the standard NEB algorithm and does not introduce additional parameters. We present applications to the isomerization of alanine dipeptide, the elimination of hydrogen from ethane and the healing of a 5-77-5 defect in graphene.