Ab initio simulations of the K-edge shift along the aluminum Hugoniot.

We develop a first-principles approach to calculate the near-edge absorption spectrum of dense plasmas based on density functional electronic structure calculations and molecular dynamics simulations. We apply the method to the calculation of the K-edge shift along the aluminum shock compressed Hugoniot. We obtain a good agreement with measurements performed at moderate compression and find that the variation of the XANES spectra could be used as a signature for melting along the Hugoniot. We also show that the calculation of the K-edge shift along the Hugoniot formally requires a fully self-consistent calculation beyond the frozen-core approximation and provides an opportunity to test the accuracy of first principle simulation methods in the high-pressure high-temperature regime.