Analysis and minimization of dislocation interactions with atomistic/continuum interfaces

Abstract

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 500 MPa for dislocations within a few Angstroms of the interface and can remain significant at distances of ∼20 Å on the atomistic side and ∼15 Å 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 Rcore = 50 Å 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 Å 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.