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Automatic adaptivity in the fully nonlocal quasicontinuum method for coarse‐grained atomistic simulations
Author(s) -
Tembhekar I.,
Amelang J. S.,
Munk L.,
Kochmann D. M.
Publication year - 2016
Publication title -
international journal for numerical methods in engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.421
H-Index - 168
eISSN - 1097-0207
pISSN - 0029-5981
DOI - 10.1002/nme.5438
Subject(s) - verlet integration , polygon mesh , computer science , lattice (music) , multiscale modeling , statistical physics , suite , computational science , voronoi diagram , algorithm , molecular dynamics , physics , geometry , mathematics , computer graphics (images) , chemistry , archaeology , history , computational chemistry , quantum mechanics , acoustics
Summary The quasicontinuum (QC) method is a concurrent scale‐bridging technique that extends atomistic accuracy to significantly larger length scales by reducing the full atomic ensemble to a small set of representative atoms and using interpolation to recover the motion of all lattice sites where full atomistic resolution is not necessary. While traditional QC methods thereby create interfaces between fully resolved and coarse‐grained regions, the recently introduced fully nonlocal QC framework does not fundamentally differentiate between atomistic and coarsened domains. Adding adaptive refinement enables us to tie atomistic resolution to evolving regions of interest such as moving defects. However, model adaptivity is challenging because large particle motion is described based on a reference mesh (even in the atomistic regions). Unlike in the context of, for example, finite element meshes, adaptivity here requires that (i) all vertices lie on a discrete point set (the atomic lattice), (ii) model refinement is performed locally and provides sufficient mesh quality, and (iii) Verlet neighborhood updates in the atomistic domain are performed against a Lagrangian mesh. With the suite of adaptivity tools outlined here, the nonlocal QC method is shown to bridge across scales from atomistics to the continuum in a truly seamless fashion, as illustrated for nanoindentation and void growth. Copyright © 2016 John Wiley & Sons, Ltd.