The effect of lithium intercalation on the electronic structure of the ternary compound semiconductors ZrSe2−xSx

Abstract

The electronic properties of the lithium intercalated layered transition metal dichalcogenide semiconductors ZrSxSe2−x for x = 0–2 have been calculated by density functional theory (DFT) using the WIEN2k code. The calculations have been carried out by the PBE functional and the TB-MBJ potential as proposed by Tran and Blaha. The calculations have been performed with and without spin–orbit coupling and reveal that the intercalation of lithium causes the conduction bands of LiZrSxSe2−x to shift by about 2 eV towards lower binding energy. From this, a Fermi level crossing and metallic behavior in the three intercalated compounds result. Moreover, a number of trends can be observed. Due to the contributions of the dichalcogenide p-states in the valence band the inclusion of SO coupling in the calculations lifts the degeneracy at the points Γ and A of the Brillouin zone in the same way as in the parent compounds. With regard to crystal field effects for each compound the splitting is larger at the A point than at the Γ point and the absolute value of the splitting increases with the atomic number of the chalcogenide. In particular, the simple Fermi surface consisting solely of barrels centered along the LML line makes LiZrSxSe2−x a promising Fermi liquid reference compound.