The Effect of the Exchange Interaction on the Dielectric Constant of the Itinerant Electrons

In this paper we present a self‐consistent treatment of the effect of the exchange interaction on the dielectric response of each spin band of an itinerant electron system. Our equation gives a simple physical picture for the role of exchange interaction, as well as that of the direct Coulomb interaction, in the dielectric responses both for the paramagnetic and ferromagnetic state. In the ferromagnetic state, the self‐consistent inclusion of the exchange interaction effect leads to a rather drastic result in which the electrons of one spin band can be repelled by a positive point charge while the electrons of the opposite spin band can be attracted.