Single Layer PbI2 : Hydrogenation-driven Reconstructions
  By performing density functional theory-based calculations, we investigate how hydrogen atom interacts with the surfaces of monolayer PbI2 and how one and two side hydrogenation modify its structural, electronic, and magnetic properties. Firstly, it was shown that T-phase of single layer PbI2 is energetically favorable than the H-phase. It is found that hydrogenation of its surfaces is possible through the adsorption of each hydrogen on iodine sites. While H atoms do not form a particular bonding-type at low concentration, by increasing the number of hydrogenated I-sites well-ordered hydrogen patterns are formed on PbI2 matrix. In addition, we found that for one-side hydrogenation, the structure forms a (2x1) Jahn-Teller type distorted structure and band gap is dramatically reduced compared to hydrogen-free single layer PbI2 . Moreover, in the case of full-hydrogenation, the structure also possesses another (2x2) reconstruction with reduction in the band gap. Easy-tunable electronic and structural properties of single layer PbI2 by hydrogenation reveal its potential use in nanoscale semiconducting device applications. 
C. Bacaksiz and H. Sahin
cond-mat.mes-hall