Parallel J-W Monte Carlo Simulations of Thermal Phase Changes in Finite-size Systems

The thermodynamic properties of 59 TeF6 clusters that undergo temperature-driven phase transitions have been calculated with a canonical J-walking Monte Carlo technique. A parallel code for simulations has been developed and optimized on SUN3500 and CRAY-T3E computers. The Lindemann criterion shows that the clusters transform from liquid to solid and then from one solid structure to another in the temperature region 60-130 K.Comment: 4 pages, 5 figures; presented at the conference on computational physics, Aachen (2001) accepted for publication in Comp.Phys.Com

Charge Dependence of Temperature-Driven Phase Transitions of Molecular Nanoclusters: Molecular Dynamics Simulation

Phase transitions (liquid-solid, solid-solid) triggered by temperature changes are studied in free nanosized clusters of TeF_6 (SF_6) with different negative charges assigned to the fluorine atoms. Molecular dynamics simulations at constant energy show that the charge increase from q_F=0.1 e to q_F=0.25 e shifts the melting temperature towards higher values and some of the metastable solid states disappear. The increased repulsive interaction maintains the order in molecular systems at higher temperatures.Comment: 4 pages, 8 figures; presented at the conference on computational physics, Aachen (2001) accepted for publication in Comp.Phys.Com