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Seamless elastic boundaries for atomistic calculations

: Pastewka, L.; Sharp, T.A.; Robbins, M.O.


Physical Review. B 86 (2012), No.7, Art.075459, 12 pp.
ISSN: 0163-1829
ISSN: 1098-0121
ISSN: 0556-2805
European Commission EC
FP7-PEOPLE; 272619; Topography Evolution
Journal Article
Fraunhofer IWM ()
atomistic-continuum coupling; lattice Green's functions; contact mechanics

Modeling interfacial phenomena often requires both a detailed atomistic description of surface interactions and accurate calculations of long-range deformations in the substrate. The latter can be efficiently obtained using an elastic Green's function if substrate deformations are small. We present a general formulation for rapidly computing the Green's function for a planar surface given the interatomic interactions, and then coupling the Green's function to explicit atoms. The approach is fast, avoids ghost forces, and is not limited to nearest-neighbor interactions. The full system comprising explicit interfacial atoms and an elastic substrate is described by a single Hamiltonian and interactions in the substrate are treated exactly up to harmonic order. This concurrent multiscale coupling provides simple, seamless elastic boundary conditions for atomistic simulations where near-surface deformations occur, such as nanoindentation, contact, friction, or fracture. Applications to surface relaxation and contact are used to test and illustrate the approach.