Mixed atomistic and continuum methods offer the possibility of carrying out
simulations of material properties at both larger length scales and longer
times than direct atomistic calculations. The quasicontinuum method links
atomistic and continuum models through the device of the finite element met
hod which permits a reduction of the full set of atomistic degrees of freed
om. The present paper gives a full description of the quasicontinuum method
, with special reference to the ways in which the method may be used to mod
el crystals with more than a single grain. The formulation is validated in
terms of a series of calculations on grain boundary structure and energetic
s. The method is then illustrated in terms of the motion of a stepped twin
boundary where a critical stress for the boundary motion is calculated and
nanoindentation into a solid containing a subsurface grain boundary to stud
y the interaction of dislocations with grain boundaries. (C) 1999 Elsevier
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