Comparison of Dissipative Particle Dynamics and Langevin thermostats for out-of-equilibrium simulations of polymeric systems

摘要

In this work we compare and characterize the behavior of Langevin andDissipative Particle Dynamics (DPD) thermostats in a broad range ofnon-equilibrium simulations of polymeric systems. Polymer brushes in relativesliding motion, polymeric liquids in Poiseuille and Couette flows, andbrush-melt interfaces are used as model systems to analyze the efficiency andlimitations of different Langevin and DPD thermostat implementations. Widelyused coarse-grained bead-spring models under good and poor solvent conditionsare employed to assess the effects of the thermostats. We consideredequilibrium, transient, and steady state examples for testing the ability ofthe thermostats to maintain constant temperature and to reproduce theunderlying physical phenomena in non-equilibrium situations. The commonpractice of switching-off the Langevin thermostat in the flow direction is alsocritically revisited. The efficiency of different weight functions for the DPDthermostat is quantitatively analyzed as a function of the solvent quality andthe non-equilibrium situation.