Molecular Dynamics Simulations and XAFS (MD-XAFS)

Abstract

MD-XAFS (Molecular Dynamics X-ray Adsorption Fine Structure) makes the connection between simulation techniques that generate an ensemble of molecular configurations and the direct signal observed from X-ray measurement. Due to the fact that the signal is most sensitive to the structure nearest to a photoelectron source, an understanding of XAFS signal is an exquisite tool for decoding the nearest neighbor coordination and correlated structure of the solvent molecules surrounding the photo-electron source. The XAFS signal can be constructed from an ensemble of scattering paths. Often the signal cannot be decomposed into a few dominant paths with characteristics that can be fitted. MD-XAFS takes advantage of the direct correspondence between the ensemble of molecular configurations and the ensemble of scattering paths, taking into account the complex correlation between them resulting in the observed signal. Due to the fact that significant phenomena are controlled by solvent response and fluctuations, such as diffusion and speciation of species, the establishment of the connection between molecular simulation and experiment has established utility in materials and catalysis systems.