A direct molecular orbital dynamics study on the hydrogen atom trapped in crystalline silicon

A direct molecular orbital (MO) dynamics method was applied to the hydrogen atom trapped in a crystalline silicon model cluster. The cluster Si26H32 was considered as a model of a silicon lattice. The full dimensional PM3-MO potential energy surface was used for the dynamics calculations. Two trapping sites for the hydrogen in the Si lattice, the interstitial tetrahedral (T) site and the Si–Si bond-center (BC) site (i.e., Si⋯H⋯Si), were examined. The calculations have shown that the hydrogen can be trapped in a T-site at low temperatures, whereas the hydrogen trapped in the T-site is easily transferred to the BC site by thermal activation at a higher temperature (∼30 K). The reaction of H atoms trapped in a silicon lattice is discussed on the basis of the theoretical results.