libvdwxc is a library of density functionals, which can be linked by density
functional theory (DFT) codes, to enable the calculation of exchange and
correlation energies for van der Waals density functionals (vdW-DF). libvdwxc
evaluates correlation energy and potential using a convolution in Fourier space
using the method by Roman-Perez and Soler.

WWW: https://libvdwxc.org/