  Vacancy-mediated diffusion of an Al atom in pure Mg matrix is studied using
the atomistic, on-lattice self-learning kinetic Monte Carlo (SLKMC) method.
Activation barriers for vacancy-Mg and vacancy-Al atom exchange processes are
calculated on-the-fly using the climbing image nudged-elastic band method and
binary Mg-Al modified embedded-atom method interatomic potential. Diffusivities
of an Al atom obtained from SLKMC simulations show the same behavior as
observed in experimental and theoretical studies available in the literature,
that is, Al atom diffuses faster within the basal plane than along the c-axis.
Although, the effective activation barriers for Al-atom diffusion from SLKMC
simulations are close to experimental and theoretical values, the effective
prefactors are lower than those obtained from experiments. We present all the
possible vacancy-Mg and vacancy-Al atom exchange processes and their activation
barriers identified in SLKMC simulations. A simple mapping scheme to map an HCP
lattice on to a simple cubic lattice is described, which enables the simulation
of HCP lattice using on-lattice framework. We also present the pattern
recognition scheme which is used in SLKMC simulations to identify the local Al
atom configuration around a vacancy.
