The structure of the bulk and the (001) surface of V2O5. A DFT+U study

PABLO L. DAMMIG QUIÑA; VICTOR A. RANEA

Materials Research Express

IOP Publishing

Lugar: Bristol; Año: 2016 vol. 3 p. 8500501 - 8500511

GGA(PW91)+U is applied to the calculation of the structure (lattice parameters) and the electronic structure of theV2O5 bulk and its (001) surface for different values of Ueff used in the literature (0.0, 3.0 and 6.6 eV). Similar surface lattice parameters are calculated for the (001) surface and for the bulk, as well as similar electronic structures. The calculated lattice parameters (a and b for the surface and a, b and c for the bulk) are in good agreement with experimental results. It seems that there is no strong correlation between the calculated lattice parameters and the value of Ueff. The calculated width of the valence band keeps the value of 5 eV for the three studied Ueff. However, the energy gap between the valence and the conduction bands increases with the value of Ueff. Ueff =3.0 eV seems to be the mostadequate value to describe the energy gap after comparison with experimental results. Electronic density contour plots indicate that for a larger (smaller) Ueff the accumulated charge in the V-O(1) bond is overestimated (underestimated). The contour plots (in the a direction) show that the charge distribution V-O(3) is less correlated with Ueff than the charge distribution V-O(1), whereas charge distribution V-O(2) seems not to be corretaled with Ueff. The energy gap between the valence and the conduction bands seems to be strongly related with the charge distribution in the V-O(1) bond. The V-O(1) bond stability seems to be correlated with Ueff. However, the stability of the V-O(2) and V-O (3) bonds seems not to be strongly affected by Ueff.