Frozen thermal fluctuations in adsorbate-induced step restructuring

Ammonia adsorbed on a Pt(443) surface causes meandering of the initially straight edges at 300 K. Based on density-functional theory calculations and on kinetic Monte Carlo simulations it is shown that the meandering is not an equilibrium structure stabilized by the larger adsorption energy of ammonia at step and kink sites. Rather the meandering has to be interpreted as a frozen thermal fluctuation caused by ammonia which strongly reduces the stiffness of the step edges at intermediate ammonia coverages.