  }We present a formalism for extending the second moment tight-binding model,
incorporating ferro- and anti-ferromagn etic interaction terms which are needed
for the FeCr system. For antiferromagnetic and paramagnetic materials, an
explicit additional variable representing the spin is required. In a mean-field
approximation this spin can be eliminated, and the potential becomes explicitly
temperature dependent. For ferromagnetic interactions, this degree of freedom
can be eliminated, and the formalism reduces to the embedded atom method (EAM)
and we show the equivale nce of existing EAM potentials to "magnetic"
potentials.
