Calculations were performed concerning various multivacancies. It was found that there existed stable sizes and structures (magic numbers). For any value of the chemical potential of the H atom, the stable multivacancy was either free from, or completely decorated with, H atoms. It was noted that a H-decorated multivacancy was capable of trapping an H2 molecule; even after H-decoration.

Magic Numbers of Multivacancy in Silicon and its Hydrogen Decoration T.Akiyama, A.Oshiyama: Physica B, 1999, 273-274, 516-9