Electron-thermal contribution to the equation of state model based on two-temperature quantum molecular dynamics simulations

We present results using two-temperature quantum molecular dynamics (QMD) simulations to identify the electron-thermal contributions to the equation of state (EOS) and make comparison with the Purgatorio-based model. The two-temperature approach treats the electron and the ion temperature independently in a QMD simulation. We applied the method to some low-Z materials (B, BN, and B₄C) and a high-Z transition-metal oxide at temperatures ranging from room temperature to 10⁶ K and 1 to 5 times compression in densities. Our results suggest that the electron-thermal contribution begins to dominate around 1.2x10⁵ K (10 eV) and is material as well as density dependent. For each material, we identify the temperature-density regime where the electron-thermal contribution is independent of ionic configurations. We illustrate our findings by comparing electron pressure and specific heat with Purgatorio-based model.