Arrhenius relationship and two-step scheme in AF hyperdynamics simulation of diffusion of Mg/Zn interface

The accelerating factor (AF) method is a simple and appropriate way to investigate the atomic long-time deep diffusion at solid-solid interface. In the framework of AF hyperdynamics (HD) simulation, the relationship between the diffusion coefficient along the direction of z-axis which is normal to the Mg/Zn interface and temperature was investigated, and the AF's impact on the diffusion constant (D0) and activation energy (Q*) was studied. Then, two steps were taken to simulate the atomic diffusion process and the formation of new phases: one for acceleration and the other for equilibration. The results show that: the Arrhenius equation works well for the description of Dz with different accelerating factors; the AF has no effect on the diffusion constant D0 in the case of no phase transition; and the relationship between Q* and Q conforms to Q*=Q/A. Then, the new Arrhenius equation for AFHD is successfully constructed as Dz=D0exp[-Q/(ART)]. Meanwhile, the authentic equilibrium conformations at any dynamic moment can only be reproduced by the equilibration simulation of the HD-simulated configurations.