Analysis and minimization of dislocation interactions with atomistic/continuum interfaces

Spurious forces are shown to arise when dislocations interact with atom/continuum interfaces in some classes of multiscale models due to the use of linear elasticity in continuum descriptions of the material deformations and/or the singular dislocation fields. For Al, such forces can reach 500MPa for dislocations within a few Angstroms of the interface and can remain significant at distances of similar to 20 angstrom on the atomistic side and similar to 15 angstrom on the continuum side of the interface, inhibiting the creation of truly seamless coupling. Replacement of the continuum representation of the dislocation displacement fields by a 'template' of the full atomistic displacement fields within a radius of R-core = 50 angstrom is shown to significantly reduce the magnitude and range of the spurious forces. Implementation of the template method permits dislocations to approach within less than 10 angstrom of the interface from both atomistic and continuum sides, permitting higher accuracy in the multiscale simulations as well as reduced size of the atomistic region.

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