Revealing trend of electron momentum densities, electronic and optical response of dichalcogenides MS2-xTex (M=Ti, Zr; x=0,1,2)

Abstract

Role of replacement of S atom by Te atoms in transition metal layered dichalcogenides (MS2; M = Ti and Zr) in amending the electronic response is reported. Different exchange and correlation potentials within linear combination of atomic orbitals (LCAO) have been used to interpret the experimental momentum densities, electronic and optical properties. It is seen that Compton profiles (CPs) based on hybrid functional combining Hartree-Fock with density functional theory namely WC1LYP reconciles better with the measured momentum densities than other considered schemes of exchange and correlation potentials. More covalent character of TiSTe than that in ZrSTe as predicted by Mulliken's population is in accordance with the measured equal-valence-electron-density profiles. Moreover, electronic and optical response using the modified Becke-Johnson (mBJ) potential as facilitated in the full potential linearized augmented plane wave method are reported. From energy bands and DOS, we conclude that concentration of Te reduces band gap in ZrS2 due to lowering of Te-5p states in the unoccupied region, while the TiS2 based mixed compounds depict metallic character.