COMBINED MULTIPLE-SCATTERING SIMULATION AND HARTREE-FOCK LCAO STUDIESOF ATOMIC DISPLACEMENTS IN LIXV2O5

Lithium intercalation into the lamellar vanadium oxide LixV2O5 is only reversible below x approximate to 0.9. Insertion of larger amounts in duces an irreversible phase transition that destroys the 2D character of the host. This structural change is die to atomic displacements tha t lead from distorted square pyramidal VO5 clusters to VO6 octahedra [ 1]. In-situ XAS studies at the vanadium K edge of lithium intercalatio n into V2O5 confirmed this local increase of the symmetry and establis hed that, not only oxygen but also vanadium, move from their initial s ites, as the intercalation proceeds [2]. Starting from this structural model, we performed multiple scattering simulation (CONTINUUM code) t o understand the changes observed in the experimental XANES spectra. T hese calculations explain the new features appearing in the edge as th e lithium rate increases. Hartree-Fock LCAO calculations (CRYSTAL 92 c ode) have also been used to discuss the stability of the proposed stru ctural models, taking into account both atomic displacements and lithi um intercalation.