Electronic structure and magnetic properties of monoclinic β-Cu2V2O7: A GGA+U study

A first-principles study on monoclinic C2/c copper pyrovanadate beta-Cu2V2O7 has been performed using the generalized gradient approximation (GGA) and GGA+U method. The optimized unit-cell parameters and atomic coordinates of beta-Cu2V2O7 agree well with experimental data. The optimized crystal structure of beta-Cu2V2O7 indicates the existence of one-dimensional -Cu-Cu-Cu-Cu- chains. The electronic structure and magnetic properties were evaluated by the GGA+U calculations, which indicate that the beta-Cu2V2O7 is a semiconducting antiferromagnetic material with an indirect band gap and local magnetic moment per Cu atom of 0.73 mu(B). The intrachain exchanges for short and long Cu-Cu couples are estimated to be 6.4 and 4.1 meV, respectively, while the calculated interchain exchange (2.1 meV) is smaller, which indicate the one-dimensional character. The top of the valence band is composed of V 3d, O 2p, and Cu 3d electrons while the bottom of the conduction band is primarily composed of Cu 3d electrons. Valence electron-density distribution map indicates the V-O and Cu-O covalent bonds. Calculated partial electronic density of states strongly suggests that the V-O and Cu-O covalent bonds are mainly attributed to the overlaps of V 3d and O 2p atomic orbitals and of Cu 3d and O 2p, respectively.