The onset of disorder on a surface with a step

Abstract

The onset of roughness on isolated steps on a flat surface was studied by computer simulation of a model system with well separated steps. The steps are one atom high on a (100) surface of a face-centred cubic crystal. Imposition of periodic boundaries in two dimensions makes the steps infinitely long; they are separated by 32 atomic spacings. The steps gradually become disordered as the temperature is increased towards the bulk melting temperature, in parallel with the increase of disorder of the flat regions of the surfaces due to promotion of atoms to an overlayer. Phonon spectra in the plateau region and at the step edge are discussed and compared.