An Event-Driven Hybrid Molecular Dynamics and Direct Simulation Monte Carlo Algorithm

摘要

A novel Stochastic Event-Driven Molecular Dynamics (SEDMD) algorithm isdeveloped for the simulation of polymer chains suspended in a solvent. Thepolymers are represented as chains of hard spheres tethered by square wells andinteract with the solvent particles with hard core potentials. The algorithmuses Event-Driven Molecular Dynamics (EDMD) for the simulation of the polymerchain and the interactions between the chain beads and the surrounding solventparticles. The interactions between the solvent particles themselves are nottreated deterministically as in event-driven algorithms, rather, the momentumand energy exchange in the solvent is determined stochastically using theDirect Simulation Monte Carlo (DSMC) method. The coupling between the solventand the solute is consistently represented at the particle level, however,unlike full MD simulations of both the solvent and the solute, the spatialstructure of the solvent is ignored. The algorithm is described in detail andapplied to the study of the dynamics of a polymer chain tethered to a hard wallsubjected to uniform shear. The algorithm closely reproduces full MDsimulations with two orders of magnitude greater efficiency. Results do notconfirm the existence of periodic (cycling) motion of the polymer chain.