  We study the kinetics of ordering in Cu3Au using a model Hamiltonian derived
from the effective medium theory of chemical bonding. Monte Carlo simulations
are used to investigate universal and non-universal features of the growth
kinetics. Anisotropic scaling of the structure factor is observed in late-stage
growth of ordered domains. The anisotropy is a non-universal feature determined
by details of the microscopic model, and we find that the anisotropy observed
in the simulations is in excellent agreement with experiments on Cu3Au. The
simulations are discussed in the context of theories of unstable growth. To our
knowledge, this is the first study of kinetics in a realistic model Hamiltonian
describing the material-specific properties of Cu3Au.
