Noninteracting band model for dielectric screening in transition metals: application to paramagnetic nickel

Abstract

The static dielectric function is studied for a transition metal on the basis of a model band structure with noninteracting s and d bands. The free-electron approximation is used for electrons in the s band, while a simplified tight-binding scheme is used for the d electrons. Explicit expressions are obtained for the intraband and interband contributions to the dielectric function. The model is applied to calculate the static dielectric function for paramagnetic nickel for (3d)⁹(4s)¹ and (3d)^9.4(4s)^0.6 configurations along the three principal symmetry directions [100], [110], and [111]. The contributions due to the intraband and interband transitions are compared: It is found that the major contribution to the dielectric function is due to the intraband transitions.