Two of the most challenging problems at the frontier of contemporary electronic
structure theory are the accurate representation of intermolecular interactions and the
development of reduced-scaling algorithms applicable to large systems. To some
extent, these two problems are antithetical, since the accurate calculation of noncovalent
interactions typically requires correlated, post-Hartree–Fock methods whose
computational scaling with respect to system size precludes the application to large
systems. In this talk, I will describe our many-body molecular dynamics (MB-MD)
methodology that overcomes these limitations and enables chemically accurate
computer simulations from the gas to the condensed phase. MB-MD is a unified
molecular dynamics framework that combines chemically accurate potential energy,
dipole moment, and polarizability surfaces derived entirely from correlated electronic
structure data using “active learning” techniques with quantum dynamical methods that
explicitly account for nuclear quantum effects. The accuracy of our MB-MD
methodology is assessed here through the analysis of the properties of water from the
gas to the condensed phase with a particular emphasis on nuclear quantum effects and
vibrational spectroscopy.