Transient atomic configurations of supported gold nanocrystallites at finite temperature

A Monte Carlo method has been developed to investigate the dynamic configurations of nanometer-sized An nanocrystallites (NCs) supported on the MgO(100) surface. We have found significant concentrations of An atoms that transiently occupy adatom positions on Au(111) facets. Their concentration increases from 10(-4) per NC at 250 K to 10(-2) per NC at 550 K. A complex roughening transition involving the creation of steps on Au(111) facets is observed close to 500 K. The appreciable numbers of various local atom configurations that may transiently appear on NC at finite temperature may be important for many applications using NCs.