4

Si     -0.086661168457964     -0.153445093667103     -0.127587647313378
Si      1.322308438900281      1.410491598064096     -0.277135798408386
Si      1.438580728146456     -0.247945797136823      1.469145121403544
Si      0.059885403162094      1.202457451760800      1.664310824750570