THERMAL-STABILITY AND STRUCTURAL TRANSITION IN BE MICROCLUSTERS

Thermodynamic stabilities of Be-6-13 microclusters have been studied using Monte Carlo simulation and an ab initio many-body potential. The mean-square fluctuation of the interparticle distance and the heat capacity were monitored as a function of temperature to illustrate thermal softening of these microclusters. The melting temperatures were found to be a strongly nonmonotonic function of size with Be-6 and Be-13 exhibiting unusual thermal stability while Be-9 and Be-12, on the other hand, were found to undergo structural transition at fairly low temperatures as a precursor to melting.