Articulo
The structure of the bulk and the (001) surface of V2O5: a DFT+U study
Autor
Ranea, Víctor Alejandro
Dammig Quiña, Pablo Leandro
Institución
Resumen
GGA(PW91)+U is applied to the calculation of the structure (lattice parameters) and the electronic structure of theV<sub>2</sub>O<sub>5</sub> bulk and its (001) surface for different values of U <sub>eff</sub> 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 U<sub>eff</sub>. The calculated width of the valence band keeps the value of 5 eVfor the three studied U<sub>eff</sub>. However, the energy gap between the valence and the conduction bands increases with the value of U<sub>eff</sub>. U<sub>eff</sub>=3.0 eV seems to be the most adequate value to describe the energy gap after comparison with experimental results. Electronic density contour plots indicate that for a larger (smaller) U<sub>eff</sub> 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 U<sub>eff</sub> than the charge distribution V-O(1), where as charge distribution V-O(2) seems not to be corretaled with U<sub>eff</sub>. 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 U <sub>eff</sub>. However, the stability of the V-O(2) and V-O (3) bonds seems not to be strongly affected by U <sub>eff</sub>. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas