Electronic structure and magnetic properties of monoclinicβ-Cu2V2O7: AGGA

Abstract

A first-principles study on monoclinic C2 / c copper pyrovanadate ␤-Cu 2 V 2 O 7 has been performed using the generalized gradient approximation ͑GGA͒ and GGA+ U method. The optimized unit-cell parameters and atomic coordinates of ␤-Cu 2 V 2 O 7 agree well with experimental data. The optimized crystal structure of ␤-Cu 2 V 2 O 7 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 ␤-Cu 2 V 2 O 7 is a semiconducting antiferromagnetic material with an indirect band gap and local magnetic moment per Cu atom of 0.73 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 meV͒ is smaller, which indicate the onedimensional 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.

β-Cu2V2O7: A spin-1

“…Further on, band structure calculations suggested two alternating couplings along the spin chains. 25 Surprisingly, all the three proposals are quite different from the actual spin lattice. Below we demonstrate that empirical considerations in the experimental studies 23,24,26 do not take account of the peculiar electronic structure of β-Cu 2 V 2 O 7 , while the computational study 25 failed to resolve all the relevant exchange interactions in the compound.…”

“…[19][20][21][22] In the following, we provide an instructive example that demonstrates the relevance of these characteristics for the microscopic magnetic model. We show that the β-modification of Cu 2 V 2 O 7 , previously considered as a spin-chain or a spin-dimer compound, [23][24][25] is the best available realization of the spin- 1 2 Heisenberg model on the honeycomb lattice. To arrive at this unexpected conclusion, we first examine the crystal structure and analyze available experimental results (Sec.…”

Evaluation of Copper Vanadate (β-Cu2V2O7) as a Photoanode Material for Photoelectrochemical Water Oxidation

“…47 Since the TRMC shows that there is only minor wavelength dependency on the carrier mobility and lifetime in Cu 2 V 2 O 7 , we attribute the sharp increase in the IPCE of Cu 2 V 2 O 7 below 350 nm to a wavelength-dependent photogeneration yield in this material. Indeed, the first electronic transition in Cu 2 V 2 O 7 is a Laporte-forbidden Cu dd transition, 31,35 like in hematite. It has been suggested that such transitions do not significantly contribute to the photocurrent.…”

Sizable Excitonic Effects Undermining the Photocatalytic Efficiency of β-Cu2V2O7

“…the antiferromagnetic ground state at 0 K. 22 We perform calculations within many-body perturbation theory through the use of the self-consistent QSGW technique. An efficient exchange-correlation kernel is included to account for vertex corrections, as described in…”