Two of the most challenging problems at the interface between contemporary electronic structure theory and molecular simulations are the accurate representation of intermolecular interactions and the development of efficient algorithms applicable to large systems. To some extent, these two problems are antithetical since the accurate calculation of non-covalent interactions typically requires correlated, post-Hartree–Fock methods whose computational scaling with respect to system size precludes applications to large systems. In this talk, I will describe our new theoretical/computational framework based on a rigorous many-body expansion of the interaction energies. Specific focus will be on our MB-pol water potential derived entirely from CCSD(T) reference data in the complete basis set limit using machine learning techniques and contains many-body effects at all monomer separations as well as at all orders, in an explicit way up to the third order and in a mean-field fashion at all higher orders. The accuracy of MB-pol will be demonstrated from the analysis of the energetics across different phases, from the dimer in the gas phase to liquid water and ice. Extensions of our many-body approach to molecular simulations of complex solutions and interfaces will also be discussed.

Many-body molecular dynamics: Towards chemically accurate molecular simulations from the gas to the condensed phase

251st National Meeting (2016)

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