Semiconductors Research Papers - Academia.edu (original) (raw)

We investigate the polytypism of MoS2 via first-principles crystal structure prediction approach. In particular, we combine the random searching method, AIRSS, for crystal structure prediction, and total energy calculations, based on... more

We investigate the polytypism of MoS2 via first-principles crystal structure prediction approach. In particular, we combine the random searching method, AIRSS, for crystal structure prediction, and total energy calculations, based on density functional theory, by using CASTEP. In addition to the semiconductor, 2H/AbA BaB polytype, space group P63/mmc, and the metallic, 1T/ AbC polytype, space group P3m1, the results suggest the formation of a monoclinic, 1M/AbC, space groupP21/m, and two orthorhombic, 2O-polytypes, space groups Fmm2 and Amm2, with different stacking sequences and band structures. The first exhibits a band gap of 1.007 eV and the second a metallic band structure. In addition, other, but unstable, structures are predicted indicating that the main factor driving the polytypism in MoS2 is the relative stacking and orientation of the slabs on which the sulfur atoms are positioned. The complex equilibrium that governs the attraction-repulsion interactions between those sulfur slabs makes reason of the variety of the polytypic structures and consequent mechanical and electronic properties of MoS2