Angular-dependent core hole screening effects have been found in the cobalt K -edge x-ray absorption spectrum of LiCoO2, using high-resolution data and parameter-free general gradient approximation plus U calculations. The Co1s core hole on the absorber causes strong local attraction. The core hole screening on the cobalt nearest-neighbors induces a 2 eV shift in the density of states with respect to the on-site 1s-3d transitions, as detected in the CoK pre-edge spectrum. Our density functional theory plus U calculations reveal that the off-site screening is different in the out-of-plane direction, where a 3 eV shift is visible in both calculations and experiment. The detailed analysis of the inclusion of the core hole potential and the Hubbard parameter U shows that the core hole is essential for the off-site screening while U improves the description of the angular-dependent screening effects. In the case of oxygen K edge, both the core hole potential and the Hubbard parameter improve the relative positions of the spectral features. © 2010 The American Physical Society.
Angular dependence of core hole screening in LiCoO2: A DFT+U calculation of the oxygen and cobalt K -edge x-ray absorption spectra / Juhin, A.; De Groot, F.; Vanko, G.; Calandra, M.; Brouder, C.. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 81:11(2010). [10.1103/PhysRevB.81.115115]
Angular dependence of core hole screening in LiCoO2: A DFT+U calculation of the oxygen and cobalt K -edge x-ray absorption spectra
Calandra M.;
2010-01-01
Abstract
Angular-dependent core hole screening effects have been found in the cobalt K -edge x-ray absorption spectrum of LiCoO2, using high-resolution data and parameter-free general gradient approximation plus U calculations. The Co1s core hole on the absorber causes strong local attraction. The core hole screening on the cobalt nearest-neighbors induces a 2 eV shift in the density of states with respect to the on-site 1s-3d transitions, as detected in the CoK pre-edge spectrum. Our density functional theory plus U calculations reveal that the off-site screening is different in the out-of-plane direction, where a 3 eV shift is visible in both calculations and experiment. The detailed analysis of the inclusion of the core hole potential and the Hubbard parameter U shows that the core hole is essential for the off-site screening while U improves the description of the angular-dependent screening effects. In the case of oxygen K edge, both the core hole potential and the Hubbard parameter improve the relative positions of the spectral features. © 2010 The American Physical Society.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione