FIRST PRINCIPLES STUDY OF A NEW LARGE-GAP NONOPOROUS SILICON CRYSTAL - HEX-SI-40

We present an ab initio calculation of the structural and electronic p roperties of Si in a novel hexagonal, fourfold coordinated structure w ith 40 atoms per unit cell, obtained from the coalescence of small ful lerenic cages. Hex-Si-40 has a tubular structure, inducing confined el ectronic states near the gap, which is widened by similar to 0.4 eV wi th respect to normal silicon. This system is predicted to be a very in teresting, possibly photoluminescent material for optoelectronics.