It was noted that most kinetic Monte Carlo models relied on a pre-defined lattice that neglected dislocations, lattice mismatch and strain effects. The use of a 3D off-lattice kinetic Monte Carlo algorithm was investigated here. This method was tested by investigating impurity diffusion in a strained kinetic Monte Carlo nanowire. While faster than a molecular dynamics simulation, the most general implementation of off-lattice kinetic Monte Carlo was much slower than a lattice-based algorithm. An improved procedure was achieved for weakly strained systems by pre-computing approximate saddle point locations based on unstrained lattice structures. In this way, one gave up some of the flexibility of the general method to restore some of the computational speed of lattice-based kinetic Monte Carlo. In addition to providing an alternative approach to nano-materials simulation, this type of simulation will be useful for testing and calibrating methods that seek to parameterize the variation in the transition rates for lattice-based kinetic Monte Carlo using continuum modeling.

Simulation of Impurity Diffusion in a Strained Nanowire Using Off-Lattice KMC. W.Guo, T.P.Schulze, E.Weinan: Communications in Computational Physics, 2007, 2[1], 164-76