Coupling Phase Field Crystal and Field Dislocation Mechanics for a Consistent Description of Dislocation Structure and Elasticity

This work addresses differences in predicted elastic fields created bydislocations either by the Phase Field Crystal (PFC) model, or by static FieldDislocation Mechanics (FDM). The PFC order parameter describes the topologicalcontent of the lattice, but it fails to correctly capture the elasticdistortion. In contrast, static FDM correctly captures the latter but requiresinput about defect cores. The case of a dislocation dipole in two dimensional,isotropic, elastic medium is studied, and a weak coupling is introduced betweenthe two models. The PFC model produces compact and stable dislocation cores,free of any singularity, i.e., diffuse. The PFC predicted dislocation densityfield (a measure of the topological defect content) is used as the source(input) for the static FDM problem. This coupling allows a critical analysis ofthe relative role played by configurational (from PFC) and elastic (from staticFDM) fields in the theory, and of the consequences of the lack of elasticrelaxation in the diffusive evolution of the PFC order parameter.