Real-space finite-difference calculations of XANES spectra along the aluminum Hugoniot from molecular dynamics simulations

Individual configurations obtained from molecular dynamics simulations have been combined with a real-space finite-difference computation of x-ray absorption near edge spectra (XANES) to obtain a measurable signature of the local order in a dense (shock-)compressed material. The approach makes use of the finite-temperature neutral pseudoatom concept. K-edge XANES spectra along the principal Hugoniot of aluminum have been obtained up to the density of 7 g/cm3. The results obtained indicate that a strong local order may exist in compressed matter even for temperatures of the order of 1 eV. We found that the red shift of the onset of absorption is only a temperature effect.