Fig. 5

Snapshots of the diffusion of hydrogen in a 2 × 2× 2 primitive supercell containing two defects at 2000 K. Mg < = > 2H lies in the lower half of the image above and Si < = > Mg + 2H lies in the upper half. a A snapshot of the structure when 3 H atoms occupy the Mg vacancy, 1 Mg the Si vacancy, and one last H gravitates around the Si vacancy. The Mg atoms are represented with their trajectory (pink dotted lines) during half a picosecond. There is no diffusion of Mg. b The H trajectory is donut- and cross-shaped in the respective two defects as represented over 2 ps simulation time. c One of the three H atoms escape the Mg vacancy. The excursion lasts several tens of femtoseconds. d The escaped H atoms falls around the Si vacancy. e Trajectory of all atoms during 20 ps of simulation time. The only diffusing species is H