Peculiar thermodynamic properties of LJ<sub>N</sub> (N=39-55) clusters
Meral Eryurek, MH Güven
article (Uluslararası, Hakemli) | Yazar(lar): Meral Eryurek, MH Güven | Yıl: 2008 | Dergi/Kurum: EUROPEAN PHYSICAL JOURNAL D | İndeks: WOS.SCI | DOI: 10.1140/epjd/e2008-00094-2 — Özet: The solid-liquid phase transitions of Lennard-Jones clusters LJ(N) (N=39-55) were simulated by a microcanonical molecular dynamics meth
The solid-liquid phase transitions of Lennard-Jones clusters LJ(N) (N=39-55) were simulated by a microcanonical molecular dynamics method using Lennard-Jones potential, and their thermodynamic quantities were calculated. The caloric curves of clusters (except N=42) have S-bend. To understand this behaviour, configurational and total entropies were evaluated, and dents on the entropy curves were taken as a sign of negative heat capacity. The heat capacities were evaluated for N=39-55 clusters using configurational entropy data. The potential energy distributions have bimodal behaviour for all clusters in the given range at the melting temperature. The distinct melting behaviour of LJ(42) was explained by the topology of the potential energy surface by examining the isomer distributions at phase transitions for LJ(39)-LJ(55). The isomer distributions were found to be a useful way to interpret this behaviour and melting dynamics in general. Melting temperature, latent heat and entropy change upon melting values were reported and are consistent with literature values and values calculated from bulk thermodynamic properties. The dependence of these quantities on the size of the clusters was examined and it is found that latent heat is the key quantity to determine the magic numbers.