TREND OF F-ELECTRON LOCALIZATION AND ITINERANCY IN RARE-EARTH AND LIGHT-ACTINIDE SYSTEMS

An important characteristic of correlated f-electron systems is their dual nature of having both degrees of localization and itinerancy. The ir magnetic behavior evolves with the amount of delocalization they ha ve. Rare-earth monopnictides are on the localized side, with weak delo calization related to hybridization. Uranium monopnictides are on the itinerant side, but localization cannot be fully neglected. To explore the problem from both the localized and the itinerant sides, we have been developing techniques to calculate the evolving properties of f-e lectron systems on a first principle ab initio basis. This involves: e lectronic structure calculations; calculating band-f hybridization; ca lculating Coulomb exchange interaction; and calculating magnetic order ing. In this work, we applied these techniques to evaluate the evoluti on off-electron behavior from heavy rare earths to light rare earths t o actinides. We will discuss how the degree of localization of the f e lectrons affects their hybridization and Coulomb exchange interaction with non-f band electrons, and how this influences the two-ion exchang e interaction and magnetic ordering. Our calculation is for XSb where X = Ce, Nd, Th, Er, Yb, U and for CeTe and UTe.