The First and Second Shell Correlation Analysis in Cu Metal by the Matched EXAFS PDF Projection Method

Through numerical simulation of inverse problem computation, our new method of EXAFS analysis was tested for a simple structure of copper metal. For a simulation test, we constructed a structural model with all possible paths of single and multiple scattering within 6 Å. Typically, the first-shell PDF (pair distribution function) is computed according to an algebraic equation describing the temperature dependence of specific anharmonic distribution. Through the MEPP (matched EXAFS PDF projection) method – combing iterative regularization and matched correction of Fourier filtering distortion, it is shown that the original function of anharmonic PDF is iteratively solved from the initial proximity model, even approximated in terms of non-realistic sub-shell mixture of anharmonic distribution feature. To remove the problem of extraneous pattern at intermediate PDF solution, we also tested a proper pattern fit on the anharmonic curve formula, resulting in significantly suitable convergence to the true PDF solution. Our simulation results indicate that the projection to true PDF solution is only reachable when the perfect background correction is selected. Our precision EXAFS analysis performance requires manipulating the apparent correlation between the first and second shells using a typical numerical process of first-shell matching Fourier filtering.