I want to write a short-line code which can generate some configurations of a rough interface with small alloy disorder. The problem is stated in the following: two neighboring interface layer I & II Layer I is mainly consisted of atom A, but with substitutional disorder, i.e. some sites are occupied by atom B from the layer II. the concentration of atom B in layer I is small and equal to [tex]\lambda[/tex]. The question is how to generate some configurations of this disorder. Taking a concrete example, If Layer I has [tex]12\times12=144[/tex] sites, and [tex]\lambda=0.05[/tex].