  Using a simple one-dimensional Frenkel-Kontorowa type model, we have
demonstrated that finite commensurate chains may undergo the
commensurate-incommensurate (C-IC) transition when the chain is contaminated by
isolated impurities attached to the chain ends. Monte Carlo (MC) simulation has
shown that the same phenomenon appears in two-dimensional systems with
impurities located at the peripheries of finite commensurate clusters.
