The Spin-Wave Stiffness within Density Functional Theory and the Ginzburg-Landau Functional

The stiffness constant of the stationary spin excitation is calculated employing density functional theory and the phenomenological Ginzburg-Landau energy functional in a site form. The exchange parameter of the magnetic functional is estimated within the framework of the nearest neighbours intermolecular interaction and the energy gain of non-magnetic state per atom. The stiffness constant of Fe, Co, and Ni metals is found based on the energies of spin polarization calculated numerically in the local spin density approximation by Moruzzi et al. as well as by Kübler. The calculated stiffness constants are compared with other theoretical calculations and experimental data.