Ensemble Representation of Dynamic Catalysts
Weird metastable states and how to find them
The surface of heterogeneous catalyst is subject to heat, electrochemical potential, and the coverage of adsorbates, which could render the catalytic interface dynamic, make the surface restructure, and change its chemical composition beyond recognition. At finite temperature, multiple surface states may coexist, and they could diverge in structure, composition, and reactivity. Modeling the catalysis realistically hence requires going beyond the (putative) global minimum structure of the catalyst, and including also the accessible local minima.
A better representation of the catalytic interface is hence a ensemble of metastable surface states. We can go even further to make the ensemble grand canonical to describe systems that restructures off-stoichiometrically. The population of each state can be determined by the thermodynamics of the states and statistical models. In this way, better prediction of properties can be made based on the ensemble averages, and the contribution of each state to the overall property/reactivity can be evaluated.
Constructing such an ensemble requires a huge amount of sampling. To make the minima search more efficient, I developed the Global Optimizer for Clusters, Interfaces, and Adsorbates (GOCIA), an open-source Python Package which features Grand Canonical Genetic Algorithm (GCGA).
- Review & Perspective
- Thermal Catalysis
- Electrocatalysis