Figure 1: Probabilities for structures at different temperatures for the Müller-Albe bond-order
potential of iron at zero pressure. At low temperatures the bcc structure is dominant as in real
iron. For higher temperatures the hcp structure, that is normally present at high pressures is
dominant instead of the correct fcc structure. At a bit more than 2500 K the melting point is
reached and no solid structures are found anymore.