Electronic structures of lanthanum, samarium, and gadolinium sulfides

In this study, we report our efforts to elucidate the electronic structures of two lattice structures of lanthanide sulfides (LnS and Ln₃S₄) and for three lanthanides (Ln = La, Sm and Gd) using density functional theory calculations performed with the CASTEP code. A DFT+U method was used for the corrections of on-site Coulomb interactions with U = 6 eV. The calculated electronic structures show that both lanthanum and gadolinium sulfides have metallic properties, consistent with the available experimental results. However, the calculated electronic structure of Sm₃S₄ is considerably different from those of the La₃S₄ and Gd₃S₄ and is predicted to have semiconducting properties.