The application of density functional theory to materials in the warm dense matter regime has motivated the development of exchange-correlation functionals which incorporate proper, explicit temperature dependence. Previous work has yielded fully thermal exchange-correlation free energy functionals at the local density approximation and generalized gradient approximation (GGA) levels of refinement. Recently, an additive thermal correction scheme was utilized to construct a meta-GGA exchange-correlation (XC) functional in which thermal effects are treated at the GGA level. The $f\mathrm{TSCAN}$ free-energy XC functional presented here includes thermal effects through the meta-GGA level in the context of the SCAN (strongly constrained and appropriately normed) ground-state functional. The $f\mathrm{TSCAN}$ functional provides generality while achieving similar performance to a thermal GGA functional at high temperatures, e.g., pressures within 1% of path integral Monte Carlo simulations of warm dense hydrogen and a significant improvement over ground-state functionals. At low temperatures, $f\mathrm{TSCAN}$ demonstrates improvements in accuracy relative to lower-level and deorbitalized functionals, indicating that calculations using $f\mathrm{TSCAN}$ may be expected to perform well across experimentally relevant densities and pressures.

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• Density functional theory
• Density functional theory development
• Meta-GGA