Ab initio simulation of polyamorphic phase transition in hydrogenated silicon -: art. no. 035209

We study the pressure-induced phase transition of a hydrogenated amorphous silicon model with a void, using a constant pressure ab initio technique within the generalized gradient approximation. With the application of pressure, the 223 atom model of hydrogenated amorphous silicon with a 5-atom void undergoes a first order phase transition from a semiconducting low density amorphous state to a metallic high density amorphous state with a discontinuous volume change of about 16%. The transition is accompanied by a coordination change from fourfold to about sixfold.