First-principles calculation of spectral features, chemical shift and absolute threshold of ELNES and XANES using a plane wave pseudopotential method

Abstract

Spectral features, chemical shifts, and absolute thresholds of electron energy loss near-edge structure (ELNES) and x-ray absorption near-edge structure (XANES) for selected compounds, i.e. TiO(2) (rutile), TiO(2) (anatase), SrTiO(3), Ti(2)O(3), Al(2)O(3), AlN and β-Ga(2)O(3), were calculated by a plane wave pseudopotential method. Experimental ELNES/XANES of those compounds were well reproduced when an excited pseudopotential, which includes a core hole, was used. In addition to the spectral features, it was found that chemical shifts among different compounds were also reproduced by correcting the contribution of the excited pseudopotentials to the energy of the core orbital.

Quasiparticle lifetime broadening in resonant x-ray scattering ofNH4NO3

“…The DFT calculations are done using pseudopotentials which lack 1 s states. However, following previous, DFT-based spectroscopy investigations we reduce this free parameter to a single calibration [1, 26–28]. We compensate for the changed chemical environment around the nitrogen core-hole site and for each site calculate the 1 s energy $${\epsilon }_{\mathrm{normalN}1s}=\mathrm{normal\Delta }{\epsilon }_{\mathrm{normalN}1s}+\frac{1}{2}Wfalse({\tau }_{\mathrm{N}}false)+V_{\text{KS}}false({\tau }_{\mathrm{N}}false),$$ where W is the screened Coulomb potential of the core hole and V KS is the total Kohn-Sham potential, both evaluated at the core-hole site τ .…”

Electronic and Chemical State of Aluminum from the Single- (K) and Double-Electron Excitation (KLII&III, KLI) X-ray Absorption Near-Edge Spectra of α-Alumina, Sodium Aluminate, Aqueous Al3+·(H2O)6, and Aqueous Al(OH)4–

“…38 XANES calculations were performed at the Al K-edge for the aqueous octahedral Al 3+ , α-Al 2 O 3 , aqueous tetrahedral Al-(OH) 4 − , and tetrahedral sodium aluminate (NaAlO 2 ) systems, respectively. Previous studies of the Al K-edge XANES have used a plane-wave pseudopotential method 39,40 for Al, AlN, and α-Al 2 O 3 , and studies of aqueous Al(H 2 O) 6 3+ clusters using both "transition state" DFT 41 and a discrete variational (DV) molecular orbital methods. 42,43 In all the ΔSCF and XANES calculations the Sapporo-QZP-2012 all electron basis set 44 was used for the single absorbing Al site, whereas the surrounding O and H atoms were treated with the 6-311G** basis set 45 and the Stuttgart RLC ECPs 46 were used to treat the surrounding Al atoms in the solid-state α-Al 2 O 3 , and tetrahedral sodium aluminate systems, respectively.…”

Supported Ga-oxide Catalyst for Dehydrogenation of Ethane

“…It is also necessary to evaluate the core electron contribution. Details of transition energy calculations were described in an earlier report 27) .…”