Bonding Characteristics and Magnetic Coupling Interactions in One-dimensional α′-NaV_2O_5

摘要

The spin-polarized generalized gradient approximation(GGA)+U approach was employed to study the bonding characteristics and magnetic coupling interactions in room-temperature phase α′-NaV2O5. The calculated results indicate that the Vdxy orbital is split off from other 3d orbitals in the VO5 pyramidal ligand field. The Vdxy orbitals are hybridized strongly with the Opx/py orbitals, forming a V―O―V π bond in the ab plane. The ligand field effect together with the intra-atomic exchange splitting results in the insulating behavior. With the aid of Noodleman's broken symmetry methods, the magnetic exchange constant was derived from mapping the relative energies onto the Heisenberg model. The antiferromagnetic(AFM) exchange energy, J, along the chain was calculated to be -593 K in good agreement with the experimental data.