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 Cu2Te 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.