Fully Automated Nanoscale to Atomistic Structure from Theory and X-Ray Spectroscopy Experiments

Photocatalytic reactions often require multiple coordinated reaction steps in a series of electron and proton transfers. It is critical to extract the oxidation state and atomic configuration of transition metal catalysts to understand the photocatalytic reaction mechanism and optimize the catalytic rate and total yield. X-ray Transient Absorption spectroscopy can be used to perform in-situ mechanistic studies, but theoretical insight requires searching a vast structural space where it is critical to not only match experimental data but to also minimize other quantities such as the energy to ensure that the structures are both physically plausible and realizable. The structural space is further complicated by the simultaneous presence of multiple molecular species. In response, we have extended our previously developed FANTASTX (Fully Automated Nanoscale to Atomistic Structure from Theory and eXperiment) code, a multi-objective evolutionary algorithm which performs structure search using genetic algorithm and basin hopping methods, to include full support for x-ray spectroscopy simulations. To search the multi-molecular structural space more efficiently, we have further extended FANTASTX by incorporating structural fingerprinting and clustering methods, enabling the identification of fundamentally different molecular candidates which can be uniformly prioritized through a novel cluster-driven evolutionary algorithm approach.