132 / 2025-03-15 16:22:56

Effect of thermal exchange-correlation functionals on the properties of warm dense matter investigated by extended first-principles molecular dynamics method

Warm Dense Matter,First-principles calculation,equation of state

Due to significant temperature effect in warm dense matter (WDM), zero-temperature exchange-correlation functionals in density functional theory, which are widely employed in condensed matter physics, can no longer accurately describe physical properties of WDM. Recently, an extended first-principles molecular dynamics (ext-FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the traditional FPMD method in the calculation of dense plasmas. Using such a unified method, we report a consistent wide-range equation of state (EOS) and principal Hugoniot of silicon, which may serve as a benchmark for the development of high-precision first-principles methods. Also, taking beryllium as an illustrating example, we provide a set of important properties including electronic structure, equation of state, principal Hugoniot, specific heat capacity, diffusion coefficients and isochoric Grüneisen parameter, calculated by ext-FPMD method across a wide range of conditions (density ρ = 3.0−9.0 g/cm³, temperature T = 10 − 10000 eV). By incorporating the finite-temperature exchange-correlation effect of electrons, we quantitatively investigate the effects of the thermal exchange-correlation functional on the modeling of these properties and emphasize their importance and necessity in the WDM regime, although it vanishes in the nondegenerate and fully degenerate limits. Our work provides a systematical evaluation of the accuracy of the previous first-principles data obtained by the zero-temperature exchange-correlation functionals, and is helpful to better understand the behavior of ions and electrons under extreme condition which is of essential importance for high-energy-density physics.