First principles investigation of the structure and electronic properties of Cu₂Te

By means of ab initio random structure search, we have revealed the crystal structure of Cu₂Te, which is in agreement with the experimentally proposed Nowotny's model. We have then performed extensive calculations based on density functional theories (DFT) on this Cu₂Te structure. We have shown that the strong on-site Coulomb repulsion among the localized Cu 3d electrons has to be included via the addition of a proper U in order to describe the crystal structure precisely. Furthermore, the Te-Te bond in Cu ₂Te shows the feature of van der Waals bonding, while the Cu-Te and Cu-Cu bonding are mainly strong covalent. By analyzing the density of states and electronic band structure, we have shown that Cu₂Te is a metallic conductor. Finally, the existence of a special Dirac-like cone at the K point in the electronic band structure of Cu₂Te reminisces that observed in graphene and topological insulators.