Computational prediction of L-3 EXAFS spectra of gold nanoparticles from classical molecular dynamics simulations

Article

关键词: RAY-ABSORPTION SPECTROSCOPY;    FINNIS-SINCLAIR POTENTIALS;    MULTIPLE-SCATTERING;    COMPUTED SPECTRA;    AQUEOUS-SOLUTION;    XANES;    CATALYSTS;    SURFACE;    ALLOYS;   

DOI  :  10.1103/PhysRevB.83.115409

来源: SCIE

【 摘 要 】

We present a computational approach for the simulation of extended x-ray absorption fine structure (EXAFS) spectra of nanoparticles directly from molecular dynamics simulations without fitting any of the structural parameters of the nanoparticle to experimental data. The calculation consists of two stages. First, a molecular dynamics simulation of the nanoparticle is performed and then the EXAFS spectrum is computed from snapshots of structures extracted from the simulation. A probability distribution function approach calculated directly from the molecular dynamics simulations is used to ensure a balanced sampling of photoabsorbing atoms and their surrounding scattering atoms while keeping the number of EXAFS calculations that need to be performed to a manageable level. The average spectrum from all configurations and photoabsorbing atoms is computed as an Au L-3-edge EXAFS spectrum with the FEFF 8.4 package, which includes the self-consistent calculation of atomic potentials. We validate and apply this approach in simulations of EXAFS spectra of gold nanoparticles with sizes between 20 and 60 angstrom. We investigate the effect of size, structural anisotropy, and thermal motion on the gold nanoparticle EXAFS spectra and we find that our simulations closely reproduce the experimentally determined spectra.

【 授权许可】

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