Electronic and optical response of zirconium sulphoselenides: Compton spectroscopy and first-principles calculations

We present the first ever experimental Compton profiles (CPs) of ZrSSe2 and ZrS1.5Se1.5 using 100 mCi Am-241 Compton spectrometer. To analyze the experimental momentum densities, we have computed for the first-time the CPs, energy bands and density of states using linear combination of atomic orbitals ([CAD) method. To model the exchange and con elation effects within [CAD approach, we have considered Hartree-Fock (HF), density functional theory (DFT) with revised functional of Perdew-Becke-Emzerhof (PBEsol) and hybridization of HF and DFT. Going beyond computation of electronic properties using [CAD method, we have also derived electronic and optical properties using the modified Becke-Johnson (mBJ) potential within full potential linearized augmented plane wave (FP-LAPW) method. There is notable decrease in the energy band gap on replacing S by Se atoms in ZrSSe2 to obtain ZrS1.5Se1.5 composition, which is mainly attributed to readjustment of Zr-4d, S-3p and Se-4p states. It is seen that the CPs based on hybridization of HU and DFT show a better agreement with the experimental profiles than those based on individual HE. and DUT-GGA-PBEsol schemes. The optical properties computed using FP-LAPW-mBJ method unambiguously depict feasibility of using both the sulphoselenides in photovoltaics and also utility of ZrS1.5Se1.5 in the field of non-linear optics. (C) 2015 Elsevier B.V. All rights reserved.