Linkage between atomistic and mesoscale coarse-grained simulation

To reduce computational cost in large scale molecular simulations and to adjust the simulation methods to multiscale nature of complex materials, it is effective to treat several atoms (or molecules) as one element. Dissipative particle dynamics (DPD) and Brownian dynamics (BD) simulations are typical examples of such coarse-graining methods. In the coarse-grained (CG) simulation methods, linkage between molecular and mesoscale parameters is important to assess accuracy and applicability of these methods. For that purpose, we derived equation of motion for the CG particles by using projection operator method which will be appeared on a subsequent paper. In the derived equation, the force acting on the CG particles is divided into the mean force, friction force and random force. In this study, we calculated the mean force between CG particles by molecular dynamics (MD) simulations with constraints. We also showed the universality of the calculated mean forces.