Coarse projective kMC integration: forward/reverse initial and boundary value problems

Publication Year
2004

Type

Journal Article
Abstract

In "equation-free" multiscale computation a dynamic model is given at a fine, microscopic level; yet we believe that its coarse-grained, macroscopic dynamics can be described by closed equations involving only coarse variables. These variables are typically various low-order moments of the distributions evolved through the microscopic model. We consider the problem of integrating these unavailable equations by acting directly on kinetic Monte Carlo microscopic simulators, thus circumventing their derivation in closed form. In particular, we use projective multi-step integration to solve the coarse initial value problem forward in time as well as backward in time (under certain conditions). Macroscopic trajectories are thus traced back to unstable, source-type, and even sometimes saddle-like stationary points, even though the microscopic simulator only evolves forward in time. We also demonstrate the use of such projective integrators in a shooting boundary value problem formulation for the compulation of "coarse limit cycles" of the macroscopic behavior, and the approximation of their stability through estimates of the leading "coarse Floquet multipliers". (C) 2003 Elsevier Inc. All rights reserved.

Journal
Journal of Computational Physics
Volume
196
Issue
2
Pages
474-489
Date Published
05/2004
ISBN
0021-9991
Short Title
J. Comput. Phys.