Hybrid atomistic-coarse-grained treatment of multiscale processes in heterogeneous materials: A self-consistent-field approach

Authors

Dennis J. Diestler, University of Nebraska-LincolnFollow
H. Zhou, University of Nebraska-Lincoln
Ruqiang Feng, University of Nebraska-LincolnFollow
Xiao Cheng Zeng, University of Nebraska-LincolnFollow

Date of this Version

8-1-2006

Comments

Published by American Institute of Physics. J. Chem. Physics125, 064705 2006. ©2006 American Institute of Physics. Permission to use. http://jcp.aip.org/.

Abstract

A treatment of multiscale quasistatic processes that combines an atomistic description of microscopic heterogeneous (“near”) regions of a material with a coarse-grained (quasicontinuum) description of macroscopic homogeneous (“far”) regions is presented. The hybrid description yields a reduced system consisting of the original atoms of the near regions plus pseudoatoms (nodes of the coarse-graining mesh) of the far regions, which interact through an effective many-body potential energy V_eff that depends on the thermodynamic state. The approximate nature of V_eff gives rise to “ghost forces,” which are reflected in spurious heterogeneities close to interfaces between near and far regions. The impact of ghost forces, which afflict all previous hybrid schemes, is greatly diminished by a self-consistent-field hybrid atomistic-coarse-grained (SCF-HACG) methodology. Tests of the SCF-HACG technique on a fully three-dimensional prototypal model [Lennard-Jones (12,6) crystal] yield thermo-mechanical properties (e.g., local stress) in good agreement with “exact” properties computed in the fully atomistic limit. The SCF-HACG method is also successfully used to characterize the grain boundary in a Lennard-Jones bicrystal.