Computing Surface Reaction Rates by Adaptive Multilevel Splitting Combined with Machine Learning and Ab Initio Molecular Dynamics

TL;DR

This paper introduces a novel approach combining Adaptive Multilevel Splitting, machine learning, and ab initio molecular dynamics to accurately compute surface reaction rates, addressing challenges in catalysis modeling.

Contribution

The study develops an integrated method that improves reaction rate calculations by effectively identifying reaction coordinates and capturing entropic effects in catalytic processes.

Findings

AMS can yield rate constants up to 100 times smaller than static methods.

Machine learning approaches help identify better reaction coordinates.

The method successfully models water dissociation on alumina surfaces.

Abstract

Computing accurate rate constants for catalytic events occurring at the surface of a given material represents a challenging task with multiple potential applications in chemistry. To address this question, we propose an approach based on a combination of the rare event sampling method called Adaptive Multilevel Splitting (AMS) and ab initio molecular dynamics (AIMD). The AMS method requires a one dimensional reaction coordinate to index the progress of the transition. Identifying a good reaction coordinate is difficult, especially for high dimensional problems such a those encountered in catalysis. We probe various approaches to build reaction coordinates such as Support Vector Machine and path collective variables. The AMS is implemented so as to communicate with a DFT-plane wave code. A relevant case study in catalysis: the change of conformation and the dissociation of a water molecule chemisorbed on the (100) $\gamma$-alumina surface is used to evaluate our approach. The calculated rate constants and transition mechanisms are discussed and compared to those obtained by a conventional static approach based on the Eyring-Polanyi equation with harmonic approximation. It is revealed that the AMS method may provide rate constants which are smaller than the static approach by up to two orders of magnitude due to entropic effects involved in the chemisorbed water.