No abstract

No abstract

Implications of the turing completeness of reactiondiffusion models, informed by GPGPU simulations on an XBox 360: Cardiac arrhythmias, re-entry and the halting problem.

We present a number of n-fold way kinetic Monte Carlo simulations of the glide motion of 90°partial dislocations in silicon. We undertake a survey of ratios of kink formation energy F k to kink migration barrier W m , over a range of temperatures and applied stresses. These simulations are compared with Hirth-Lothe theory and an extension to the Hirth-Lothe theory of Kawata and Ishiota. The latter is found to give the best description of the system. Using literature first principle values for the kink and soliton formation and migration energies, a model combining both strained bond and soliton mediated motion shows a negligible contribution to dislocation motion from the solitons. The high soliton pair creation barrier was limiting and a soliton mediated mechanism for dislocation motion would have to achieve thermal equilibrium concentration via impurity or point defect interaction to be effective. We also show that if this can be overcome solitons greatly increase the mobility of the dislocation, even without a binding energy between solitons and kinks. The simulation coded here is easily expandable to incorporate further dislocation line effects such as impurities at the line.

We review first-principles calculations of dislocation core structure in diamond, and draw out similarities with and differences from silicon. Primary differences are in hybridization changes in carbon and in the different behaviour of H interacting with dislocations. In both materials, condensation of a homogeneous distribution of H atoms should result, first, in formation of small H aggregates with the appearance of a glide dislocation dipole and, second, in formation of larger platelets based on the half-stacking-fault model.