科研之友
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摘要
The electronic structure of room-temperature (RT) phase alpha'-NaV2O5 has been investigated by fully self-consistent first-principles calculations based on density functional theory (DFT). For the crystallographic unit cell, a nonmagnetic (NM) metallic solution is obtained by spin-restricted generalized gradient approximation (GGA) calculations, whereas a ferromagnetic (FM) insulating solution is successfully simulated within the spin-polarized GGA. An insulating antiferromagnetic (AFM) state with lower energy is obtained for the 1 x 2 x 1 crystallographic supercell. The magnetic S = 1/2 electrons are fully spin-polarized and delocalized on the V-O-V molecular orbitals (along the rung), where the net spin magnetic moments amount to 0.96 mu(B) on the V-O-V rungs of the ladder derived from Mulliken population analysis. The intra-rung vanadium d(xy) orbitals form the bonding-antibonding orbitals split by inter-orbital interactions. It is not the on-site Coulomb interaction, but the AFM spin exchange couplings that lead to the half-filled bonding orbitals splitting and forming a magnetic insulating gap. The present spin-polarized DFT calculations reveal that alpha'-NaV2O5 (RT) is a Slater insulator. The calculated electronic structure explains the controversial topics of the absorption peak in the optical spectra and the energy loss peak in the resonant inelastic x-ray scattering (RIXS).
