Generalized Gradient Approximation Made Thermal

Applications of warm dense matter include inertial confinement fusion, models of exoplanet interiors, and

matter under extreme shock conditions - all of which have been studied using DFT. Most successful

simulations, however, use existing ground-state approximations to the exchange-correlation free energy.

While this may be valid in both the low- and high-temperature limits, the quantitative ramifications of this

approximation are unknown and may be crucial to our current understanding of warm dense matter. To

correct this, we generate the temperature-dependence of PBE through a sequence of Kohn-Sham CP-DFT

calculations [1, 2] that yield accurate exchange-correlation holes at finite temperatures. We propose a

temperature-dependent generalized gradient approximation stemming from the characteristics of the

thermal exchange-correlation holes of PBE. We discuss the form of this approximation, and compare its

results with existing suggestions in the literature.

[1] R. J. McCarty, et al. “Bypassing the Energy Functional in Density Functional Theory: Direct Calculation of

Electronic Energies from Conditional Probability Densities.” Phys. Rev. Lett. 125, 266401 (2020).

[2] D. Perchak, et al. “Correlation Energy of the Uniform Gas Determined by Ground State Conditional

Probability Density Functional Theory.” Phys. Rev. B 105, 165143 (2022).