Exchange-Correlation Thermal Effects: Softening the Deuterium Hugoniot and Thermophysical Properties
V.V. Karasiev and S.X. Hu
Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14623-1299
Exchange-correlation (XC) thermal effects for transport and optical properties of deuterium along the principal Hugoniot are investigated. A study is performed using ab initio molecular dynamics (AIMD) simulations within the Mermin–Kohn–Sham density functional theory. XC thermal effects are taken into account via temperaturedependent generalized gradient approximation functional. 1 In this talk, we will briefly discuss some details of the formal developments of the new XC free-energy functional that bridges low-temperature (ground-state) and high-temperature (plasma) limits and therefore takes into account XC thermal effects, and report main results. We find that XC thermal effects account for softening of the Hugoniot at pressures P > 250 GPa and improve agreement with recent experimental measurements. Also, XC thermal effects lead to a reflectivity increase by ~2% for shock speeds above 20 km/s. Calculated reflectivity for shock speeds up to 50 km/s is in good agreement with recent experimental measurements on the OMEGA Laser System. The dc conductivity is increased by ~4% because of XC thermal effects. Therefore, XC thermal effects must be taken into account for accurate predictions of matter properties in the warm dense regime.
This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE- NA0003856 and US National Science Foundation PHY Grant No. 1802964.
1V. V. Karasiev, J. W. Dufty, and S. B. Trickey, Phys. Rev. Lett. 120, 076401 (2018).