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DOE OSTI · 1602230

Towards accurate orbital-free simulations: A generalized gradient approximation for the noninteracting free energy density functional

Luo, K.·Karasiev, V. V.·Trickey, S. B.
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Abstract

For orbital-free ab initio molecular dynamics, especially on systems in extreme thermodynamic conditions, we provide the first pseudo-potential-adapted generalized gradient approximation (GGA) functional for the non-interacting free energy. This is achieved by systematic finite-temperature extension of our recent LKT ground state non-interacting kinetic energy GGA functional (Phys. Rev. B 98, 041111(R) (2018)). We test the performance of the new functional first via static lattice calculations on crystalline aluminum and silicon. Then we compare deuterium equation of state results against both path-integral Monte Carlo and conventional (orbital-dependent) Kohn-Sham results. The new functional, denoted LKTF, outperforms the previous best semi-local free energy functional, VT84F (Phys. Rev. B 88, 161108(R) (2013)), and provides modestly faster simulations. Finally, we discuss subtleties of identification of kinetic and entropic contributions to non-interacting free-energy functionals obtained by extension from ground state orbital-free kinetic energy functionals.

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71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICSGGAdensity functional theory developmentwarm-dense matter

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Luo, K., Karasiev, V. V., Trickey, S. B.. 2020-02-13. Towards accurate orbital-free simulations: A generalized gradient approximation for the noninteracting free energy density functional. https://doi.org/10.1103/physrevb.101.075116

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