Linear response and density functional theory for the spin-polarized electron gas

Abstract

The connection between the kernals in a perturbation expansion for the electron energy in density functional theory and the response functions is considered, with particular reference to a ferromagnetic electron gas with a uniform direction of magnetization. For this special case, the long-wavelength limits of the ferromagnetic susceptibilities are related self-consistently to the energy functional for the spin-polarized electron gas. Using information about the paramagnetic response functions, it is shown how approximate forms can be found for the kernels entering both the ferromagnetic susceptibilities and the density-gradient expansion for the electron energy.