Variational density functional perturbation theory for metals
Xavier Gonze, Samare Rostami, Christian Tantardini
Abstract
Density Functional Perturbation Theory (DFPT) is a proven method for analyzing molecular and solid responses to perturbations. For metals, challenges arise due to Fermi-Dirac statistics and electronic bands crossing the Fermi energy. This work focuses on variational DFPT for metals, examining the convexity of the entropy function of occupation numbers. It emphasizes benefits from resmearing Fermi-Dirac broadening at finite temperature, details variational expressions for free energy derivatives, and addresses inaccuracies in unperturbed wavefunctions. The formalism is implemented in the ABINIT software.
Topics & Concepts
Wave functionPhysicsFermi Gamma-ray Space TelescopePerturbation (astronomy)Formalism (music)Perturbation theory (quantum mechanics)Variational principleQuantum mechanicsDensity functional theoryConvexityStatistical physicsQuantum electrodynamicsMusicalArtFinancial economicsVisual artsEconomicsHigh-pressure geophysics and materialsAdvanced Chemical Physics StudiesSuperconductivity in MgB2 and Alloys