LIBEFP is a full implementation of the Effective Fragment Potential (EFP)
method (EFP can be viewed as an advanced first-principles-based force-field,
see Kaliman et al., JCC, 2013). LIBEFP facilitates extension of unique
electronic structure methodologies designed for accurate simulations in the
gas phase to condensed phases via QM/EFP. LIBEFP is designed to give developers
of quantum chemistry software an easy way to add EFP support to their favourite
package.

WWW: https://libefp.github.io