Mixed Stochastic-Deterministic Density Functional Theory Within The PAW Formalism: An Efficient Approach To Warm Dense Matter*

Warm dense matter (WDM), believed to form the cores of exoplanets and dwarf stars, has gathered considerable interest recently due to its realization in inertial confinement fusion. Monumental efforts in experiment as well as theoretical/computational modeling have inched toward elucidating the properties and nonequilibrium dynamics of WDM. In computational materials modeling, density functional theory (DFT) is a powerful tool employed for studying systems ranging from just a few molecules to much more condensed phases. However, the cubic scaling of DFT with system size and temperature renders much of the WDM regime computationally intractable. White and Collins have developed a formalism [1] that mixes the stochastic and deterministic algorithms of DFT to study matter at any temperature. The idea behind mixed DFT is to improve efficiency by introducing stochastic orbitals while at the same time maintaining the accuracy of a deterministic Kohn-Sham DFT computation. In this work, we implement projector augmented wave (PAW)-based pseudopotentials in the mixed DFT formalism. PAW potentials are more accurate and computationally inexpensive compared to most other pseudopotentials, and therefore enhance our ability to investigate a wide area in the (temperature, pressure)-phase space of matter. In this talk, we present results obtained with semicore- and core electrons- PAW for carbon systems in the WDM domain, and compare them with simpler, norm-conserving Goedecker pseudopotentials.

[1] A. J. White and L. A. Collins, Phys. Rev. Lett. 125, 055002 (2020).