Structure of a sheared soft-disk fluid from a nonequilibrium potential

Abstract

The distortion of structure of a simple, inverse-12, soft-disk fluid undergoing two-dimensional plane Couette flow was studied by nonequilibrium molecular dynamics (NEMD) simulation and by equilibrium Monte Carlo (MC) simulation with a nonequilibrium potential, under which the equilibrium structure of the fluid is that of the nonequilibrium fluid. Extension of the iterative predictor-corrector method of [Reatto et al.Phys. Rev. A 33 3451 (1986)] was used to extract the nonequilibrium potential with the structure input from the NEMD simulation. Very good agreement for the structural properties and pressure tensor generated by the NEMD and MC simulation methods was found, thus providing the evidence that nonequilibrium liquid structure can be accurately reproduced via simple equilibrium simulations or theories using a properly chosen nonequilibrium potential. The method developed in the present study and numerical results presented here can be used to guide and test theoretical developments, providing them with the "experimental" results for the nonequilibrium potential.

Flow Effects on Melt Structure and Entanglement Network of Linear Polymers: Results from a Nonequilibrium Molecular Dynamics Simulation Study of a Polyethylene Melt in Steady Shear

“…In addition, as the flow strength is increased: (a) the characteristic peaks in the g inter ( r ) plots become more pronounced, and (b) the positions of the peak shift slightly to the left; both of these observations are indicative of a flow-enhanced packing of the atomistic units in the simulated melt. We also point out the more intensified oscillatory behavior of g inter ( r ) with the flow strength which indicates an enhancement of structural and spatial correlations between chains; this has been quantitatively reported in an NEMD study of a sheared soft-disk fluid, by introducing a long-range potential representative of the nonequilibrium fluid structure.…”