  Structure-based coarse graining of molecular systems offers a systematic
route to reproduce the many-body potential of mean force. Unfortunately, common
strategies are inherently limited by the molecular mechanics force field
employed. Here, we extend the concept of multisurface dynamics, initially
developed to describe electronic transitions in chemical reactions, to
accurately sample the conformational ensemble of a classical system in
equilibrium. In analogy to describing different electronic configurations, a
surface-hopping scheme couples distinct conformational basins beyond the
additivity of the Hamiltonian. The incorporation of more surfaces leads
systematically toward improved cross-correlations. The resulting models
naturally achieve consistent long-time dynamics for systems governed by
barrier-crossing events.
