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.