Atomic scale modelling of the cores of dislocations in complex materials part 2: applicationsFor part 1 see ref. 1.Electronic supplementary information (ESI) available: Figs. S1–S6 (see text) and xyz files of the structures of the dislocations in Figs. 6, 7 and 10. See http://dx.doi.org/10.1039/b505716g

In an accompanying article, we have described a methodology for the simulation of dislocations in structurally complex materials. We illustrate the applicability of this method through studies of screw dislocations in a structurally simple ionic ceramic MgO, a molecular ionic mineral forsterite, Mg2SiO4, a semi-ionic zeolite siliceous zeolite A and a covalent molecular crystalline material the pharmaceutical, orthorhombic paracetamol-II. We focus on the extent of relaxation and the structure of the dislocation cores and comment on similarities and points of disparity between these materials. It is found that the magnitude of the relaxation varies from material to material and does not simply correlate with the magnitude of the principal elastic constants in an easily predictable fashion, or with the size of the cohesive lattice energy or length of the Burgers vector, which emphasises the need to model the non-linear forces and atomic structure of the core.