The physics of the principle for the simulation depends on the type of simulations.
surface segregation in film/substrate system (available from April 2009)
Segregation of substrate atoms on the surface of a film is predicted by comparing the adsorption energy of a substrate atom on film material with that on substrate material. The principle of simulation is explained in more detail in the literature [Michiko Yoshitake, Yarrama-Reddy Aparna, and Kazuhiro Yoshihara, J. Vac. Sci. Technol., A 19, 2001, pp. 1432-1437.]
The principle of simulation UNDER OXYGEN ATMOSPHERE (available from August 2012) is explained in the literature [Michiko Yoshitake, Jpn. J. Appl. Phys., 51, 2012, 085601.]
surface segregation in dilute alloy system (available in the future)
interface segregation at film-substrate interface (available in the future)
interface segregation at alloy-substrate interface (available in the future)