Thermal stability and structural transition in Be microclusters

Thermodynamic stabilities of ${\mathrm{Be}}_{6–13}$ 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 ${\mathrm{Be}}_6$ and ${\mathrm{Be}}_{13}$ exhibiting unusual thermal stability while ${\mathrm{Be}}_9$ and ${\mathrm{Be}}_{12}$, on the other hand, were found to undergo structural transition at fairly low temperatures as a precursor to melting.