Finite-temperature orbital-free DFT molecular dynamics: coupling Profess and Quantum Espresso

Abstract

Implementation of orbital-free free-energy functionals in the Profess code and the coupling of Profess with the Quantum Espresso code are described. The combination enables orbital-free DFT to drive ab initio molecular dynamics simulations on the same footing (algorithms, thermostats, convergence parameters, etc.) as for Kohn-Sham (KS) DFT. All the non-interacting free-energy functionals implemented are single-point: the local density approximation (LDA; also known as finite-T Thomas-Fermi, ftTF), the second-order gradient approximation (SGA or finite-T gradient-corrected TF), and our recently introduced finite-T generalized gradient approximations (ftGGA). Elimination of the KS orbital bottleneck via orbital-free methodology enables high-T simulations on ordinary computers, whereas those simulations would be costly or even prohibitively time-consuming for KS molecular dynamics (MD) on very high-performance computer systems. Example MD simulations on H over a temperature range 2,000 K <= T <=4,000,000 K are reported, with timings on small clusters (16-128 cores) and even laptops. With respect to KS-driven calculations, the orbital-free calculations are between a few times through a few hundreds of times faster.

References in corpus (7)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Path Integral Monte Carlo Simulation of the Warm-Dense Homogeneous Electron Gas
• Local Spin-density Approximation Exchange-correlation Free-energy Functional
• Issues and Challenges in Orbital-free Density Functional Calculations
• Non-empirical Generalized Gradient Approximation Free Energy Functional for Orbital-free Simulations
• Constraint-based, Single-point Approximate Kinetic Energy Functionals
• Comparison of Density Functional Approximations and the Finite-temperature Hartree-Fock Approximation in Warm Dense Lithium

Cited by in corpus (24)

• The Uniform Electron Gas at Warm Dense Matter Conditions
• Ab initio Exchange-Correlation Free Energy of the Uniform Electron Gas at Warm Dense Matter Conditions
• Ab initio simulation of warm dense matter
• The importance of finite-temperature exchange-correlation for warm dense matter calculations
• A Simple Generalized Gradient Approximation for the Non-interacting Kinetic Energy Density Functional
• Kubo-Greenwood Electrical Conductivity Formulation and Implementation for Projector Augmented Wave Datasets
• Nonempirical Semi-local Free-Energy Density Functional for Matter Under Extreme Conditions
• First principles simulations of dense hydrogen
• Extended First-Principles Molecular Dynamics Method From Cold Materials to Hot Dense Plasmas
• Influence of finite temperature Exchange-Correlation effects in Hydrogen
• DFTpy: An efficient and object-oriented platform for orbital-free DFT simulations
• Non-local kinetic energy functional from the Jellium-with-gap model: applications to Orbital-Free Density Functional Theory
• Frank Discussion of the Status of Ground-state Orbital-free DFT
• Towards accurate orbital-free simulations: a generalized gradient approximation for the non-interacting free energy density functional
• Jellium-with-gap model applied to semilocal kinetic functionals
• The equation of state of partially ionized hydrogen and deuterium plasma revisited
• Multiple Scattering Theory for Dense Plasmas
• Equation of state, phonons, and lattice stability of ultra-fast warm dense matter
• First-principles derivation and properties of density-functional average-atom models
• Entropy and canonical ensemble of hybrid quantum classical systems
• Effect of Ionic Disorder on the Principal Shock Hugoniot
• Nuclear cusps and singularities in the non-additive kinetic potential bi-functional from analytical inversion
• Hybrid quantum-classical systems: statistics, entropy, microcanonical ensemble and its connection to the canonical ensemble
• Higher-order finite-difference formulation of periodic Orbital-free Density Functional Theory