Expanded-volume phases of silicon: Zeolites without oxygen

Abstract
By reducing the (4;2)-connected regular three-dimensional nets of zeolites to 4-connected nets, we introduce a variety of new expanded structures of elemental Si. An ab initio molecular dynamics method is used to determine the optimized geometries, energetics, and electronic properties of the proposed structures. It is found that Si structures derived from those of group-6 (5-ring) zeolites are particularly low in energy (∼0.1 eV/atom above the ground state) and semiconducting (with band gaps varying ±0.7 eV about the 1.17 eV gap of diamond Si). © 1996 The American Physical Society.