Occupation Potential Versus Coulomb Correlation Energy in 4-f Insulators

Abstract

Hufner and Werteim’s estimate the correlation energy between 4fⁿ and 4f^n+l configurations by photoemission experiments to be of the order of 6 eV while others give a value of ~10.5 eV. We have established a method based on the energy differences per unit cell with two configurations as a Coulomb correlation, from the band structure and an estimation of the collective effects by perturbative methods which by introducing the U correlation in the MT potential allows us to find the excited states showing some hybridation and deslocalization and a widening of 4f bands. This broadening could explain the discrepancy observed in the above experimental results.