  The Ising antiferromagnet on a face-centered cubic (fcc) lattice with
nearest-neighbor interaction only is well known to exhibit a macroscopic
(exponential in the system size $L$) ground-state degeneracy. With increasing
temperature, this degeneracy is expected to be lifted and the model undergoes a
first-order phase transition. For a model with an exponential degeneracy in the
whole low-temperature phase, it was recently found that the finite-size scaling
behavior is governed by leading correction terms $\sim L^{-2}$ instead of $\sim
L^{-3}$ as usual. To test the conjecture that such a transmuted behavior may
effectively persist also for the fcc antiferromagnet up to some crossover
system size, we have performed parallel multicanonical Monte Carlo simulations
for lattices of linear size $L \le 18$ with periodic boundary conditions and
determined various inverse pseudo phase transition temperatures, as well as the
extremal values of the specific heat and the energetic Binder parameter. We
indeed find that, for the simulated lattice sizes, the conjectured transmuted
finite-size scaling ansatz fits the data better than the standard ansatz. On
this basis, we extrapolate for the transition temperature an estimate of $T_0 =
1.735047(46)$.
