A bridging domain method for coupling continua with molecular dynamics

A bridging domain method for coupling continuum models with molecular models is described. In this method, the continuum and molecular domains are overlapped in a bridging subdomain, where the Hamiltonian is taken to be a linear combination of the continuum and molecular Hamiltonians. We enforce the compatibility in the bridging domain by Lagrange multipliers or by the augmented Lagrangian method. An explicit algorithm for dynamic solutions is developed. Results show that this multiscale method can avoid spurious wave reflections at the molecular/continuum interface without any additional filtering procedures, even for problems with significant nonlinearitics. The method is also shown to naturally handle the coupling of the continuum energy equation with the molecular subdomain. A multiple-time-step algorithm is also developed within this framework. (C) 2004 Elsevier B.V. All rights reserved.