Adiabatic Connection Methods Applied to Molecular Crystals

We extend adiabatic connection models (ACMs) derived from the Møller-Plesset adiabatic connection (MPAC) formalism, previously applied only to finite systems, to periodic molecular crystals. Lattice energies for 19 representative systems are computed and compared with periodic MP2, high-level reference, and experimental data. The tested ACMs achieve accuracies comparable to state-of-the-art dispersion-corrected hybrid density functionals and come close to those of correlated wave function methods. Among them, the HFAC24 model, which is a post-Hartree-Fock parameter-free correlation expression that correctly recovers both the uniform electron gas and strong-interaction limits, is the only one with accurate binding energies and accurate total energies. The results in this work demonstrate that MPAC-based ACMs provide an accurate and transferable framework for modeling molecular-crystal energetics and represent a robust, systematically improvable route for developing correlation models for extended systems.