Multiparticle Collision Dynamics: Simulation of Complex Systems on Mesoscales

Abstract

Complex systems can display complex phenomena that are not easily described at a microscopic level using molecular dynamics simulation methods. Systems may be complex because some or all of their constituents are complex molecular species, such as polymers, large biomolecules, or other molecular aggregates. Such systems can exhibit the formation of patterns arising from segregation of constituents or nonequilibrium effects and molecular shape changes induced by flows and hydrodynamic interactions. Even when the constituents are simple molecular entities, turbulent fluid motions can exist over a range of length and time scales.Many of these phenomena have their origins in interactions at the molecular level but manifest themselves over mesoscopic and macroscopic space and time scales. These features make the direct simulation of such systems difficult because one must follow the motions of very large numbers of particles over very long times. These considerations have prompted the development of coarse-grain methods that simplify the dynamics or the system in different ways in order to be able to explore longer length and time scales. The use of mesoscopic dynamical descriptions dates from the foundations of nonequilibrium statistical mechanics. The Boltzmann equation [1] provides a field description on times greater than the time of a collision and the Langevin equation [2] replaces a molecular-level treatment of the solvent with a stochastic description of its properties.The impetus to develop new types of coarse-grain or mesoscopic simulation methods stems from the need to understand and compute the dynamical properties of large complex systems. The method of choice usually depends on the type of information that is desired. If properties that vary on very long distance and time scales are of interest, the nature of the dynamics can be altered, while still preserving essential features to provide a faithful representation of these properties. For example, fluid flows described by the Navier-Stokes equations will result from dynamical schemes that preserve the basic conservation laws of mass, momentum, and energy. The details of the molecular interactions may be unimportant for such applications. Some coarsegrain approaches constructed in this spirit, such as the lattice Boltzmann method [3] and direct simulation Monte Carlo [4], are based on the Boltzmann equation. In dissipative particle dynamics [5, 6], several atoms are grouped into simulation sites whose dynamics is governed by conservative and frictional 90 raymond kapral 92 raymond kapral

Hydrodynamic simulations of self-phoretic microswimmers

“…Over the last decades various mesoscopic simulation methods have been developed to bridge such an enormous gap. Here, we employ an especially convenient hybrid scheme that describes the solvent by MPC which is a coarse-grained particle-based method [23][24][25][26][27][28], while the interactions of the Janus particle with the solvent are simulated by standard molecular dynamics (MD).…”

Emergence of metachronal waves in cilia arrays

“…To describe the dynamics of the surrounding fluid, we use the multiparticle collision dynamics (MPC) approach, a particlebased mesoscale hydrodynamic simulation technique that naturally includes thermal fluctuations (33,34). We use the effective temperature inherent to our fluid-dynamics model to mimic the noise present in any biological system.…”

Semidilute Polymer Solutions at Equilibrium and under Shear Flow

“…The solvent is simulated by the multiparticle collision (MPC) dynamics method [23,24,45,46]. It is composed of N s point-like particles of mass m, which interact with each other by a stochastic process.…”

“…Here, we apply a hybrid simulation approach, combining molecular dynamics simulations (MD) for the polymers with the multiparticle collision dynamics (MPC) method describing the solvent [23,24,27,[45][46][47][48][49][50]. As has been shown, the MPC method is very well suited to study the non-equilibrium properties of polymers [12,41,51,52], colloids [13,53,54], and other soft-matter object such as vesicles [55] and cells [56,57] in flow fields.…”

“…Due to the long structural relaxation time, the internal degrees of freedom of a polymer cannot relax sufficiently fast under non-equilibrium conditions and an elastic restoring force tries to push the system towards its original state. Here, a deeper understanding can be achieved by mesoscale hydrodynamic simulations [23,24].…”