Cluster melting coexistence

The argument regarding the link between local minima in the free energy and the coexistence of two phases over a band of temperarure and pressure (or of any two state variables) is not restricted to only two phases. Just as more than two chemical isomers may coexist, more than two phases of a cluster may coexist. There is nothing essential that prohibits the appearance of multiple minima in the free energy. This is perhaps clearest if the order parameter is not a simple scalar but a vector characterizing more than one property of the system. While a variety of kinds of clusters have been objects of study for surface melting, d5i-i53,i64-i83 example is... 

Figure 9. Power spectra at several energies for Ar,3 cluster, (a) In limit rigid portion of caloric curve at = —4.92 x 10" erg/atom. (b) Rigid limit form near melting, = —4.36 x 10 erg/atom. Notice softening of distinct modes. Zero intensity at cu = 0 is still maintained, however, (c) Spectrum of high-temperature form in coexistence region, = —4.13 x 10" erg/atom. (d) Spectrum of low-temperature form at same energy, (e) Spectrum at an energy in limit liquid portion of caloric curve, = -3.61 x 10 erg/atom.

Figure II. N-dependent melting temperatures and coexistence temperature ranges A7. a—longtime averaged kinetic energy values at which rms bond length fluctuations S rise sharply (see Fig. 10). Dashed lines correspond to coexistence temperature ranges AT = T — 7) ) for clusters that display a bimodal form for short-time averaged temperatures. (Beck et al. )...

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