Tight-binding based non-collinear spin model and magnetic correlations in iron

We have extended a first principles tight-binding total energy model to include magnetic correlations. We have tested the validity of the model against ab-initio calculations for bcc and fcc Fe. We find that our model can quantitatively describe the pressure dependence of magnetic moments and magnetization energy for bcc and fcc Fe. Moreover, in fcc Fe with increasing pressures it is able to capture the transitions from ferromagnetic to non-collinear spin to antiferromagnetic and finally to the non-magnetic state.