Unusual Electronic Structure of Few-Layer Grey Arsenic: A Computational   Study
  We use ab initio density functional theory to study the equilibrium geometry and electronic structure of few-layer grey arsenic. In contrast to the bulk structure that is semimetallic, few-layer grey As displays a significant band gap that depends sensitively on the number of layers, in-layer strain, layer stacking and inter-layer spacing. A metal-semiconductor transition can be introduced by changing the number of layers or the in-layer strain. We interpret this transition by an abrupt change in the spatial distribution of electronic states near the top of the valence band. 
Zhen Zhu, Jie Guan and David Tomanek
cond-mat.mes-hall cond-mat.mtrl-sci