A Systematic Density Functional Theory Study of V_xO_y⁺ and V_xO_Y (X = 2−4, Y = 2−10) Systems

Abstract

A theoretical study on geometrical, thermodynamic and electronic properties of V x O y + and V x Oy (x = 2−4, y = 2−10) systems in different electronic states has been carried out. Analytical gradient techniques with a hybrid spin unrestricted and spin restricted Hartree−Fock density functional method (B3LYP) have been used. An analysis of potential energy surfaces at ground and some excited states renders the most stable structures an their corresponding vibrational frequencies. The reaction energies of the possible decomposition channels are reported and the results indicate that the formation of larger clusters is energetically favorable from the smaller VO+ (3∑), VO (4∑), VO2 (2A1), VO3 (2A‘),V2O4 (3A‘ ‘) and V2O5 (1A‘) systems and O2 (3∑g). A comparative discussion of the bonding in these species has been carried out on the basis of the topological analysis of the electron localization function. Numerical results are analyzed and confronted with available experimental data.

Reactivity of the V2O5–TiO2-anatase catalyst: role of the oxygen sites

“…The simplest model consists of a V 2 O 5 unit that can be linear (O 2 VOVO 2 ) or cyclic (OVO 2 VO 2 ) as shown in figure 1. The latter is the most favorable by 0.68 eV according to our calculations (0.82 eV [21], 0.62 eV [22]). In this structure, one vanadium atom is three-fold coordinated while the other is four-fold coordinated.…”

“…There are two reasons for the use of clusters to represent the active phase: first, active species on the catalyst surface are known to be dispersed as monomers or dimers [9,[14][15][16][17][18][19], and second because of their stability in gas phase already investigated by collision-induced dissociation, CID, experiments [20] and DFT calculations [21,22]. The cluster calculations have been performed with the Gaussian98 code [23] at a B3LYP level with a DB-31G* basis set for all atoms (see details in Ref.…”

Density functional theory study of the oxidation of methanol to formaldehyde on a hydrated vanadia cluster

“…45,46 We optimized local minima corresponding to the reactant complex, reaction intermediates, final complex, and other fragment species, and the corresponding frequency and thermodynamic properties have been obtained. We have already applied this level to calculate molecular mechanisms associated to reactions of VO 2 1 with hydrocarbons 35,36,38,47 and some water-assisted mechanism processes 47,48 as well as previous works with complex systems involving vanadium oxide systems [49][50][51] yielding satisfactory results. Therefore, we are confident with the data calculated at this computing level for this type of reaction.…”

Metall‐Metall‐Mehrfachbindung oder keine Bindung? Die elektronische Struktur von V2O2

“…[28] Daneben gibt es mehrere rechnerische Studien zu V 2 O 2 ,d ie alle eine rhombische Struktur aber verschiedene elektronische Zustände vorhersagen. Calatayud, AndrØsu nd Bertrµn [32] berechneten einen 3 A 1 -Zustand mit dem B3LYP-Funktional und dem 6-31G*-Basissatz. Jakubikova, RappØ und Bernstein [33] fanden mit dem BPW91-Funktional und dem LANL2DZ-Basissatz einen 7 A''-Zustand.…”