A limit of stability in supercooled liquid clusters
Abstract
We examine the metastable liquid phase of a supercooled gold nanocluster by studying the free energy landscape using the largest solidlike embryo as an order parameter. Just below freezing, the free energy exhibits a local minimum at small embryo sizes and a maximum at a larger critical embryo size. At T =660K the free energy becomes a monotonically decreasing function of the order parameter as the liquid phase becomes unstable, indicating that we have reached a limit of stability. In contrast to the meanfield theory predictions for a spinodal, the size of the critical embryo remains finite as the limit of stability is approached. We also calculate the rate of nucleation, independently from our free energy calculations, and observe a rapid increase in its temperature dependence when the free energy barrier is on the order of kT. We suggest that this supports the idea that freezing becomes a barrierless process at low temperatures.
 Publication:

Journal of Chemical Physics
 Pub Date:
 October 2007
 DOI:
 10.1063/1.2779875
 Bibcode:
 2007JChPh.127o4703M
 Keywords:

 65.20.+w;
 61.25.Mv;
 64.70.Dv;
 Thermal properties of liquids: heat capacity thermal expansion etc.;
 Liquid metals and alloys;
 Solidliquid transitions