Meta-GGA exchange-correlation free energy density functional to increase the accuracy of warm dense matter simulations
Valentin V. Karasiev, Deyan Mihaylov, S. X. Hu
Abstract
We discuss strategies for thermalization of the ground-state meta-generalized gradient approximation (meta-GGA) exchange-correlation (XC) functionals. A simple but accurate scheme is implemented via universal additive thermal correction to XC using a perturbativelike self-consistent approach. The additive correction with explicit temperature dependence is applied to the ground-state deorbitalized, strongly constrained, and appropriately normed (SCAN-L) meta-GGA XC leading to a thermal XC functional denoted here as T-SCAN-L. The thermal T-SCAN-L meta-GGA functional shows significant improvement in density functional theory calculation accuracy for warm dense matter by a factor of 3 to 10, achieving an accuracy of total pressure between a few tenths and $\ensuremath{\sim}1$% when compared to traditional XC functionals, as demonstrated by the comparison to path-integral Monte Carlo simulations for helium equation of state. The T-SCAN-L calculations of dc conductivity of warm dense aluminum also give better agreement with experiments over other XC functionals such as PBE and SCAN-L.