Epitaxial growth of thin films and single crystals has long been regarded as an art rather than a science. For the thin film part, a detailed atomic scale understanding of equilibrium and kinetic issues has been achieved through a combined effort of experiment and theory. We are using kinetic Monte Carlo simulations and the non-linear coupled differential equations from nucleation theory to model nucleation, growth, and coarsening. These models are compared to experiment in order to identify the key parameters, such as adatom diffusion and binding energies. Our nano-mechanical experiments are equally backed up by theoretical modeling using empirical potentials. For ab-initio calculations of experimentally determined material properties we entertain collaborations with theory groups.