Regensburg 2007 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 21: Finite size effects at phase transitions II (session accompanying the symposium of the same name)
DY 21.5: Vortrag
Mittwoch, 28. März 2007, 15:00–15:15, H3
Finite-size effects on subcritical chemical potential isotherms in two- and three-dimensional square-well fluids — •Horst Vörtler1, Katja Schäfer1, and William Smith2 — 1Institut für Theoretische Physik, Universität Leipzig, Germany — 2Faculty of Science, UOIT Oshawa, Canada
We study the influence of system size on chemical potentials of bulk square-well fluids and planar square-well films under subcritical conditions over wide ranges of densities and particle numbers using canonical MC simulations with test particle insertions. In the range between the stable vapour and liquid densities we find van der Waals-like loops in the chemical potential isotherms which show distinct finite size effects. Similarly to recent findings (MacDowell et al., J. Chem. Phys. 120(2004)5293; 125(2006)034705) for bulk Lennard-Jones fluids we observe a significant shrinking of the van der Waals-like loops with increasing number of particles for both bulk fluids and planar monolayers. In the stable gaseous and liquid ranges the system size dependence is found to be quite weak. Estimating the vapour-liquid coexistence densities from the simulated chemical potential isotherms by integration via a Maxwell equal area rule (Vörtler, Smith, J. Chem. Phys. 112(2000)5168) we find for bulk fluids only weak finite size effects on the coexistence data and the obtained results are very close to the best-known literature data. In two-dimensional layers the size effects on the coexistence data are significantly larger than on bulk conditions.