Electronic and optical properties of gyrotropic α-Hg3S2Cl2: insights from an ab initio study

The optical spectra of gyrotropic alpha-Hg(3)S(2)Cl(2)polymorph were calculated for the first time to give a deep insight into its band structure. The exchange-correlation potential was treated with the generalized gradient approximation and modified Becke-Johnson potential (MBJ) to improve the accuracy of electronic structure calculation. The detailed analysis of the low-energy electronic states near the Fermi level was conducted. The main contributions of the sulfur and chlorine p states are located at the top of the valence band, while the S/p and Hg/s states give main contribution to the bottom of the conduction band. The direct optical band gap of 3.19 eV is at the CYRILLIC CAPITAL LETTER GHE-points of Brillouin zone. The value of direct optical transitions, which was calculated by MBJ method, agrees very well with the experimental report on diffuse reflectance spectra. The reported structural and optical properties of alpha-Hg(3)S(2)Cl(2)polymorph make it a potentially interesting compound for nonlinear optical applications.

Automated summary

The optical spectra of gyrotropic alpha-Hg(3)S(2)Cl(2) polymorph were calculated for the first time, with a focus on the band structure near the Fermi level. The sulfur and chlorine p states contribute mainly to the top of the valence band, while the S/p and Hg/s states dominate the bottom of the conduction band. Additionally, the direct optical band gap was found to be 3.19 eV at specific points in the Brillouin zone, showing good agreement with experimental reports.