A multiple replica approach to simulate reactive trajectories

TL;DR

This paper introduces a parallel replica method for efficiently simulating reactive trajectories between metastable states, using a flexible reaction coordinate and extending to transition time calculations, demonstrated on simple potential models.

Contribution

The paper presents a novel parallel replica algorithm for reactive trajectory simulation that does not require an exact reaction coordinate, with an extension for transition time estimation.

Findings

Effective in simple potential models

Reliable without precise reaction coordinate

Extends to transition time computation

Abstract

A method to generate reactive trajectories, namely equilibrium trajectories leaving a metastable state and ending in another one is proposed. The algorithm is based on simulating in parallel many copies of the system, and selecting the replicas which have reached the highest values along a chosen one-dimensional reaction coordinate. This reaction coordinate does not need to precisely describe all the metastabilities of the system for the method to give reliable results. An extension of the algorithm to compute transition times from one metastable state to another one is also presented. We demonstrate the interest of the method on two simple cases: a one-dimensional two-well potential and a two-dimensional potential exhibiting two channels to pass from one metastable state to another one.