  A dynamics of the precession of coupled atomic moments in the tight-binding
(TB) approximation is presented. By implementing an angular penalty functional
in the energy that captures the magnetic effective fields self-consistently,
the motion of the orientation of the local magnetic moments is observed faster
than the variation of their magnitudes. This allows the computation of the
effective atomic magnetic fields that are found consistent with the
Heisenberg's exchange interaction, by comparison with classical atomistic spin
dynamics on Fe, Co and Ni magnetic clusters.

Materials Science