An analysis of the effect of ghost force oscillation on quasicontinuum error

Matthew Dobson, Mitchell Luskin

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

The atomistic to continuum interface for quasicontinuum energies exhibits nonzero forces under uniform strain that have been called ghost forces. In this paper, we prove for a linearization of a one-dimensional quasicontinuum energy around a uniform strain that the effect of the ghost forces on the displacement nearly cancels and has a small effect on the error away from the interface. We give optimal order error estimates that show that the quasicontinuum displacement converges to the atomistic displacement at the rate O(h) in the discrete l∞ and 1,1 norms where h is the interatomic spacing. We also give a proof that the error in the displacement gradient decays away from the interface to O(h) at distance O(h)in the atomistic region and distance O(h) in the continuum region. Our work gives an explicit and simplified form for the decay of the effect of the atomistic to continuum coupling error in terms of a general underlying interatomic potential and gives the estimates described above in the discrete l∞ and 1,1 norms.

Original languageEnglish (US)
Pages (from-to)591-604
Number of pages14
JournalMathematical Modelling and Numerical Analysis
Volume43
Issue number3
DOIs
StatePublished - May 2009

Keywords

  • Atomistic to continuum
  • Ghost force
  • Quasicontinuum

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