Electronic structure of superconducting copper intercalated transition metal dichalcogenides: First-principles calculations

We report first-principles calculations, within density functional theory, of copper intercalated titanium diselenides, CuxTiSe2, for values of x ranging from 0 to 0.11. The effect of intercalation on the energy bands and density of states of the host material is studied in order to better understand the cause of the superconductivity that was recently observed in these structures. We find that charge transfer from the copper atoms to the metal dichalcogenide host layers leads to the formation of Cu-Se bonds that stabilize most of the transferred charge on Se atoms and lead to a relatively large lowering of the Se-derived hole bands. The suppression of the hole bands, the increase in the number of electrons, and the corresponding enhancement of the density of states at the Fermi energy may contribute to the emergence of superconductivity in these systems.