Interpretation of the U L₃-edge EXAFS in uranium dioxide using molecular dynamics and density functional theory simulations

X-ray absorption spectroscopy is employed to study the local structure of pure and Cr-doped UO₂ at 300 K. The U L₃-edge EXAFS spectrum is interpreted within the multiplescattering (MS) theory using the results of the classical and ab initio molecular dynamics simulations, allowing us to validate the accuracy of theoretical models. The Cr K-edge XANES is simulated within the full-multiple-scattering formalism considering a substitutional model (Cr at U site). It is shown that both unrelaxed and relaxed structures, produced by ab initio density functional theory (DFT) calculations, fail to describe the experiment.