Constant-pressure simulations with dissipative particle dynamics

Abstract

Dissipative particle dynamics ͑DPD͒ is a mesoscopic simulation method for studying hydrodynamic behavior of complex fluids. Ideally, a mesoscopic model should correctly represent the thermodynamic and hydrodynamic properties of a real system beyond certain length and time scales. Traditionally defined DPD quite successfully mimics hydrodynamics but is not flexible enough to accurately describe the thermodynamics of a real system. The so-called multibody DPD ͑MDPD͒ is a pragmatic extension of the classical DPD that allows one to prescribe the thermodynamic behavior of a system with only a small performance impact. In an earlier paper ͓S. Y. Trofimov, E. L. F. Nies, and M. A. J. Michels, J. Chem. Phys. 117, 9383 ͑2002͔͒ we much improved the accuracy of the MDPD model for strongly nonideal systems, which are of most practical interest. The ability to correctly reproduce the equation of state of realistic systems in turn makes simulations at constant pressure sensible and useful. This situation of constant-pressure conditions is very common in experimental studies of ͑soft͒ condensed matter but has so far remained unexplored with the traditional DPD. Here, as a proof of concept, we integrate a modified version of the Andersen barostat into our improved MDPD model and make an evaluation of the performance of the new model on a set of single-and multicomponent systems. The modification of the barostat suppresses the "unphysical" volume oscillations after a sudden pressure change and simplifies the equilibration of the system.

Boundary-controlled barostats for slab geometries in molecular dynamics simulations

“…Variants of the Andersen method have been developed since [7], as well as a generalization to predefine the pressure tensor, P B [8][9][10][11], which allows the cell shape to change with time. The Andersen barostat has been applied in dissipative particle dynamics simulations by including a damping term to the equation of motion for the volume [12]. Stochastic or Langevin dynamics equations of motion for the box volume [13,14] and weak-coupling barostat schemes [15,16] have also been used in defining the bulk system barostat.…”

A single-site anisotropic soft-core model for the study of phase behavior of soft rodlike particles

“…It should be noted that the "multibody" DPD allows one to prescribe the thermodynamic behavior of a real fluid, specially in reproducing the demixing behavior of a binary mixture of compressible fluids and the gas-liquid phase equilibrium of a single component real fluid [36,37]. But in our simulations, we are focusing on the melted single-component anisotropic system, for which the density ρ is kept constant since ρ should not change drastically.…”

Droplets impact on textured surfaces: Mesoscopic simulation of spreading dynamics

“…Many-body dissipative particle dynamics (MDPD) [24,25] is the modified version of classical DPD [26,27]. MDPD adds van der Waals loop in the equation of state (EOS) so as to make it suitable for simulation of fluid systems with free liquid/vapor interface.…”