Towards accurate orbital-free simulations: a generalized gradient approximation for the non-interacting free energy density functional

Abstract

For orbital-free {\it 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 \textbf{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 \textbf{88}, 161108(R) (2013)), and provides modestly faster simulations. We also 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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• Multiple Scattering Theory for Dense Plasmas
• Imposing Correct Jellium Response Is Key to Predict the Density Response by Orbital-Free DFT
• Some Problems in Density Functional Theory
• Plane-Wave-Based Stochastic-Deterministic Density Functional Theory for Extended Systems
• Truncated Non-Local Kinetic Energy Density Functionals for Simple Metals and Silicon
• Nonlocal vs Local Pseudopotentials Affect Kinetic Energy Kernels in Orbital-Free DFT
• Nonlocal free-energy density functional for warm dense matter
• Generalized density functional theory framework for the non-linear density response of quantum many-body systems
• Nonlocal Orbital-Free Kinetic Energy Functional from the Jellium-with-Gap Model for Finite Systems
• Unlocking the Power of Orbital-Free Density Functional Theory to Explore the Electronic Structure Under Extreme Conditions