Energy Exchange between Mesoparticles and Their Internal Degrees of Freedom

We present mesoscale equations of motion that lead to a thermodynamically accurate description of the energy exchange between mesoparticles and their internal degrees of freedom. In our approach, energy exchange is done through particle coordinates, rather than momenta, resulting in Galilean invariant equations of motion. The total linear momentum and total energy (including the internal energy of the mesoparticles) are conserved, and no coupling occurs when a mesoparticle is in free flight. We test our method for shock wave propagation in a crystalline polymer, poly(vinylidene fluoride); the mesodynamics results agree very well with all-atom molecular dynamics.