Magnetic susceptibility of ferromagnetic metals: Application to nickel

Expressions for the transverse and longitudinal magnetic (spin) susceptibility of ferromagnetic metals, which have been derived from density-functional theory in the local-density approximation, are simplified and made practical for computation through a transformation from a Fourier representation to an orbital representation. The method is applied to a calculation of the transverse susceptibility of ferromagnetic nickel at $T=0\mathrm{}$. Results are obtained for spin-wave energies and widths using a semiempirical band structure.