L2,3 edge photoabsorption spectra of bulk V2O5: A two components relativistic time dependent density functional theory description with finite cluster model

Abstract

The two-component relativistic time dependent density functional theory method to treat the core electron excitations has been applied to the bulk V(2)O(5) for the description of X-ray absorption at the L edges. The theoretical method has proven accurate to reproduce the experimental NEXAFS spectrum, thanks to the inclusion of the most relevant physical effects: the crystal field, the configuration mixing, and the spin-orbit coupling. The method has been applied by taking into account suitable cluster models, accurately chosen in order to simulate at best the electronic structure of the condensed phase.

First principles calculations of the structure and V L-edge X-ray absorption spectra of V2O5 using local pair natural orbital coupled cluster theory and spin–orbit coupled configuration interaction approaches

“…[34][35][36] However, so far no relevant study has been successful in properly reproducing the V L-edge part of the spectrum. [7][8][9] Herein, we apply the DFT/ROCIS method in conjunction with a large cluster model and demonstrate that excellent agreement with experiment can be obtained without the variation of any adjustable parameter.…”

“…In particular, for transition metal L 2,3 -edge spectra the particle/hole based theories have very limited predictive capabilities. This is already evident for the case at hand, V 2 O 5 , for which, despite several attempts, [7][8][9] to date no successful calculation of the vanadium L-edge absorption spectrum has been reported. Given that this material formally contains V (V) sites with a d 0 closed-shell electronic configuration, this is somewhat surprising.…”

Investigation of the multiplet features of SrTiO3in X-ray absorption spectra based on configuration interaction calculations

“…Further, spectra calculated by DFT in the independent particle approximation taking three different types of one-electron potentials into account all give incorrect peak intensities (Krü ger, 2010). Many calculation approaches have been developed over the last decades to try to understand the L 2,3 -edge absorption spectrum: for example, time-dependent DFT, which to our knowledge has not been applied to STO but to other 3d 0 oxides such as V 2 O 5 (Fronzoni et al, 2012) and FeTiO 3 (Bunȃ u & Joly, 2012) with fairly good agreements with experimental absorption spectra; the Bethe-Salpeter equation, where the theoretical spectra either lack capturing of the peak intensities at the STO Ti L 2,3 -edges (Laskowski & Blaha, 2010;Gilmore et al, 2015) or exhibit an incorrect peak splitting between the leading peaks and the excitation peaks (Gilmore et al, 2015;Vinson et al, 2011); multichannel multiple-scattering calculations, where the calculated spectra show variations in relative peak splitting compared with the experimental STO spectrum (Krü ger, 2010;Krü ger & Natoli, 2016); and ab initio full multiplet calculations (Ikeno et al, 2009;Haverkort et al, 2012;Ramanantoanina & Daul, 2017), where the Ti L 2,3 -edges show a better description of the experimental spectrum in terms of relative peak positions and intensities. We note that all of these approaches can reproduce the STO Ti L 2,3 absorption spectrum reasonably well but demand large computational efforts which shows the advantages of understanding the spectrum of large electron systems.…”

Local geometric and electronic structures of gasochromic VOx films

“…This feature can be described in terms of molecular orbitals that comprise both a central V 3d xy component and 3d t 2g -like components of the neighboring V atoms. 35,36 Approximately 1.4 eV above A 2 is B 2 , which is a transition that is characteristic of the other two t 2g -like components, 3d xz and 3d yz . The increased intensity of this peak B 2 is caused by an increase in the 3d contribution of the excited V atoms relative to that of the peripheral V atoms in the final states.…”