  To enable accurate molecular dynamics simulations of iron-chromium alloys
with surfaces, we develop, based on density-functional-theory (DFT)
calculations, a new interatomic Fe-Cr potential in the Tersoff formalism.
Contrary to previous potential models, which have been designed for bulk Fe-Cr,
we extend our potential fitting database to include not only conventional bulk
properties but also surface-segregation energies of Cr in bcc Fe. In terms of
reproducing our DFT results for the bulk properties, the new potential is found
to be superior to the previously developed Tersoff potential and competitive
with the concentration-dependent and two-band embedded-atom-method potentials.
For Cr segregation toward the surface of an Fe-Cr alloy, only the new potential
agrees with our DFT calculations in predicting preferential segregation of Cr
to the topmost surface layer, instead of the second layer preferred by the
other potentials. We expect this rectification to foster future research, e.g.,
on the mechanisms of corrosion resistance of stainless steels at the atomic
level.
