Valence-band photoemission and optical absorption in nickel compounds

Surface properties of LiCoO2, LiNiO2 and LiNi1−xCoxO2

“…This valence band character leads to different fi nal state pathways in core-level cobalt photoemission, and is typically represented [48] The Ni 2p XP spectra (Fig. 5) provide another example of the charge-transfer nature of an octahedral 2+ cation, this time for Ni 2+ in NiO as well as for the nickel-containing lithium transition metal oxide samples.…”

Effect of electron correlations in Pd, Ni, and Co monowires

“…We will use data for NiO (in the rhombohedral structure with the antiferromagnetic phase) where we know exactly the experimental band gap which is 4.3 eV (Ref. 34). We calculated the fundamental gap in NiO with LSDA and LDA+U for U =2 eV and U =8 eV, and we obtained 0.22 eV, 0.69 eV, and 3.32 eV respectively, with the radius of the projector fixed at 2.5 a.u.…”

Correlated band structure of NiO, CoO, and MnO by variational cluster approximation

“…Starting with the work of Hubbard [11] a variety of theoretical methods have been invented to deal with this problem [12,13,14,15,16,17,18,19,20,21,22]. Major progress towards a quantitative description of 3d TM oxides has been made by the cluster method initiated by Fujimori and Minami [23,24,25,26,27] This takes the opposite point of view as compared to band theory, namely to abandon translational invariance and instead treat exactly -by means of atomic multiplet theory [28,29] -the Coulomb interaction in the 3d-shell of a TM-ion in an octahedral 'cage' of nearest-neighbor oxygen atoms. The angle-integrated valence band photoemission spectra calculated by this method are in excellent agreement with experiment [23,24,25,26,27].…”