Size and shape of three-dimensional Cu clusters on a MgO(001) substrate: Combined ab initio and thermodynamic approach

In order to describe theoretically metallic island growth at the early stages of metal deposition on oxide substrates, we combined ab initio atomic and electronic structure calculations with thermodynamic theory of solid solutions. The experimentally observed truncated pyramidal shape of metallic clusters is reproduced as the result of metal atom segregation from the lattice gas in imaginary Ising lattice towards the metal/substrate interface. Our approach is illustrated by detailed analysis of Cu islands on a MgO(001) -terminated surface. We predict dependencies of the shape and the height of such clusters on the temperature and metal gas pressure.