David Aristoff's homepage Title: Stability and Convergence for Nonequilibrium Langevin Dynamics

Abstract: The talk is interested in methods to sample particle systems that have an overall steady, homogeneous flow. One application of this dynamics is to impose a strain rate on a complex fluid or immersed molecular system in order to compute the stress-strain constitutive relation using a microscopic stress formulation. We will discuss algorithmic aspects of nonequilibrium molecular dynamics simulations in the presence of periodic boundary conditions, particularly convergence and long-term stability issues. In such a simulation the simulation box deforms with the flow, and we describe generalizations of Kraynik-Reinelt boundary conditions that allow for long-time simulation by avoiding extreme deformation of the unit cell. Care must be taken in implementing numerical integrators consistent with the deforming boundary conditions and we describe the strong convergence properties of the stochastic equations.