Direct Coulomb contribution of the conduction electrons to the crystalline electric field in cubic rare earth intermetallics

Starting from electronic APW wavefunctions the author derives the expression of the direct Coulombic contribution of the conduction electrons to the crystalline electric field in rare earth intermetallics. The results on the compounds DyRh, DyCu, LaAg, DyZn and YMg explain partially the variation and the amplitude of the fourth-order CEF parameters in the corresponding series.