New interatomic potential for simulation of pure magnesium and magnesium hydrides

Abstract

We develop an interatomic potential intended for the study of Mg-H system using atomistic methods. The reported potential has an angular-dependent form and can be used for simulation of pure magnesium, as well as for consideration of binary cases including Mg and H. Summary of the performed tests on elastic, thermophysical and diffusional properties proves that the potential has a wide range of applicability. For example, it can be used to model phase transitions existing in pure magnesium (liquid $\leftrightarrow$ hcp and bcc $\leftrightarrow$ hcp). We also show how the model represents energies of different point defects and stacking faults in Mg. The primary purpose of the potential is the simulation of hydrogen behavior in magnesium. Here we show examples of the hydrogen diffusion and clusterization in hcp magnesium. Also, it is shown that the proposed potential reproduces stable structures for some of the existing magnesium hydrides: $\alpha$-MgH₂ (P4₂/mnm) and $\gamma$-MgH₂ (Pbcn).