Pressure effects in Debye–Waller factors and in EXAFS

Anharmonic correlated Einstein model (ACEM) and statistical moment method (SMM) have been developed to derive analytical expressions for pressure dependence of the lattice bond length, effective spring constant, correlated Einstein frequency and temperature, Debye–Waller factors (DWF) or second cumulant, first and third cumulants in Extended X-ray Absorption Fine Structure (EXAFS) at a given temperature. Numerical results for pressure-dependent DWF of Kr and Cu agree well with experiment and other theoretical values. Simulated EXAFS of Cu and its Fourier transform magnitude using our calculated pressure-induced change in the 1st shell are found to be in a reasonable agreement with those using X-ray diffraction (XRD) experimental results.

Research Highlights
► We have developed anharmonic correlated Einstein model and statistical moment method.
► The pressure effects in cumulants including DWF and in EXAFS has been investigated.
► Calculated pressure-dependent DWF for Kr, Cu agree with experiment and other results.
► Simulated EXAFS and Fourier transform magnitude of Cu agree with those using XRD data.