libvdwxc: a library for exchange–correlation functionals in the vdW-DF family

Abstract

We present libvdwxc, a general library for evaluating the energy and potential for the family of vdW-DF exchange-correlation functionals. libvdwxc is written in C and provides an efficient implementation of the vdW-DF method and can be interfaced with various general-purpose DFT codes. Currently, the GPAW and Octopus codes implement interfaces to libvdwxc. The present implementation emphasizes scalability and parallel performance, and thereby enables ab initio calculations of nanometer-scale complexes. The numerical accuracy is bench-marked on the S22 test set whereas parallel performance is benchmarked on ligand-protected gold nanoparticles (Au-144(SC11NH25)(60)) up to 9696 atoms.