Improving the accuracy of warm-dense matter simulations with temperature-dependent meta-GGA exchange-correlation functional – fT(r²)SCAN

Density functional theory is the workhorse of modern electronic structure theory, with many thousands of publications annually devoted to its use and improvement, e.g. the formulation of new exchange/correlation functionals. While such work has a long history, most has been in the low temperature regime of typical quantum chemistry and condensed matter physics applications.

However, a growing body of work is devoted to DFT in the warm dense matter regime, where intense pressures and temperatures drive ground-state approximations beyond their limits. XC functionals with explicit temperature effects are needed to improve the accuracy of such DFT simulations.

Here, following the strategy adopted for fully-thermal LDA (KSDT) and GGA (KDT16) XC functionals, we present a meta-GGA XC free-energy functional with explicit temperature dependence, based on the SCAN functional: fTSCAN. fTSCAN has been benchmarked against high-temperature PIMC data and demonstrates proper low-temperature behavior for high transferability within a range of conditions from the ambient to the extreme.

We report progress as well towards an orbital-free extension of fTSCAN capable of improved scaling as well as the adaptation of fTSCAN to the regularized-restored (r²) SCAN formulation for improvements in numerical stability.



This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0004144 and US National Science Foundation PHY Grant No. 2205521.