Rapid thermal equilibration in coarse-grained molecular dynamics

Coarse-grained representations of matter are required for the investigation of material phenomena that occur simultaneously at different length and time scales. Multiple scales cause problems at finite temperature, where phonon reflection at interfaces separating different scales causes unphysical local heating in the region of the smallest (atomic) scale. A physical model is proposed, which effectively controls the temperature in coarse-grained regions while preserving correct dynamics in the atomistic region. This is achieved using a multiscale dynamic-stochastic heat bath. The validity of the model is demonstrated within the context of a coarse-grained one-dimensional Lennard-Jones chain.