Conservative Algorithm for an Adaptive Change of Resolution in Mixed Atomistic/Coarse-Grained Multiscale Simulations.

We derive a Hamiltonian and present a simulation protocol for mixed-resolution systems that allows for a change in resolution of selected groups of atoms during a molecular dynamics simulation. The Hamiltonian uses a low-resolution force field for the part of the system distant from an active site (for efficiency) and an atomistic force field for the active site and its direct environment (for accuracy). A microcanonical simulation protocol conserves energy and angular and linear momentum. The method is also applicable to simulations in other ensembles.