Exchange Stiffness Parameter and Magnetization in Pseudopotential Calculations

We study low temperature magnetic properties of transition metals. The ground state spontaneous magnetization is calculated in a pseudopotential approximation. In the calculations, the core electronic orbitals are approximated by asymptotic expressions. The magnetizations are calculated for uniform spin densities of valence (chemically active) electrons and in the Lindhard approximation. Our calculations of the Bloch wall parameter and the magnon stiffness constant are based on a study of ferromagnetic and paramagnetic phases. A simple Bragg-Williams approximation between energy of spin polarization and the time-average of the spin moment per atom determines the "exchange coupling" (Heisenberg-like) for spin-polarized nearest neighbour Wigner-Seitz cells. Ab initio numerical results of the spontaneous magnetization, the Bloch wall parameter, and the magnon stiffness constant are obtained for Fe, Co, and Ni.