  The self-consistent rate theory for surface growth in the submonolayer regime
is generalized from mono- to multi-component systems, which are formed by
codeposition of different types of atoms or molecules. As a new feature, the
theory requires the introduction of pair density distributions to enable a
symmetric treatment of reactions among different species. The approach is
explicitly developed for binary systems and tested against kinetic Monte Carlo
simulations. Using a reduced set of rate equations, only a few differential
equations need to be solved to obtain good quantitative predictions for island
and adatom densities, as well as densities of unstable clusters.
