Characterization and visualization of the lattice misfit associated with dislocation cores

Atomic misfit associated with a crystal dislocation is manifested by displacements of atoms from their positions in the perfect lattice. The discrete character of the crystal lattice and the nature of interatomic bonds distribute this misfit over the plane normal to the dislocation line. The Nye tensor, which describes the distribution of the resultant Burgers vector across a plane normal to the dislocation line, provides an excellent means of describing the spatial variation of the misfit. Relevant components of the Nye tensor are calculated from atomic positions in the dislocated crystal, represented by contour plots, and contrasted with the corresponding quantities obtained from a local continuum model. The comparison demonstrates that spatial distributions of components of the Nye tensor provide an accurate and instructive means of representing dislocation core structures. A numerical integration of these distributions permits an accurate calculation of the Burgers vector without constructing a Burgers circuit.