Libxc: A library of exchange and correlation functionals for density functional theory

The central quantity of density functional theory is the so-called exchange–correlation functional. This quantity encompasses all non-trivial many-body effects of the ground-state and has to be approximated in any practical application of the theory. For the past 50 years, hundreds of such approximations have appeared, with many successfully persisting in the electronic structure community and literature. Here, we present a library that contains routines to evaluate many of these functionals (around 180) and their derivatives.Program summaryProgram title: LIBXCCatalogue identifier: AEMU_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMU_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: GNU Lesser General Public License version 3No. of lines in distributed program, including test data, etc.: 87455No. of bytes in distributed program, including test data, etc.: 945365Distribution format: tar.gzProgramming language: C with Fortran bindings.Computer: All.Operating system: All.RAM: N.A.Classification: 7.3, 16.1.Nature of problem: Evaluation of the exchange–correlation energy functional and its derivatives. This is a fundamental part of any atomic, molecular, or solid-state code that uses density-functional theory.Solution method: The values of the energy functional and its derivatives are given in a real grid of mesh points.Running time: Typically much smaller than the remainder of the electronic structure code. The running time has a natural linear scaling with the number of grid points.