Diffusion processes of the Li+ ion on a model surface of amorphous carbon (Li+C96H24 system) were investigated by means of the direct molecular orbital dynamics method at the semi-empirical AM1 level. The total energy and energy gradient on the full-dimensional AM1 potential energy surface were calculated at each time step in the dynamics calculation. The optimized structure, where Li+ was located in the center of the cluster, was used as the initial structure at time zero. The dynamics calculation was carried out in the temperature range 100-1000K. The calculations showed that the Li+ ion vibrates around the equilibrium point below 200K, while the Li+ ion moved on the surface above 250K. At intermediate temperatures (300K < T < 400K), the ion moved on the surface and fell in the edge regions of the cluster. At higher temperatures (600K < T), the Li+ ion transfered freely on the surface and edge regions. The diffusion pathway of the Li+ ion was examined on the basis of theoretical results.

Diffusion Dynamics of the Li+ Ion on a Model Surface of Amorphous Carbon: a Direct Molecular Orbital Dynamics Study. Tachikawa, H., Shimizu, A.: Journal of Physical Chemistry B, 2005, 109[27], 13255-62