Monte Carlo simulations of squalane in the Gibbs ensemble

We investigate the liquid-vapour coexistence curve of 2,6,10, 15,19,23-hexa methyltetracosane (squalane) near the critical point with a new Lennard-Jon es parameter set and compare our results to existing simulation data as wel l as to recent experimental vapour pressure data. Comparison of the liquid- vapour coexistence curve to previous simulation data reveals that this new force field, which includes tail corrections to the truncation of the non-b onded interactions increases the Liquid density. We determine the critical temperature to 829 K and 825 K (with roughly 1% error) for two different sy stem sizes, 72 and 108 molecules, and the critical density to 0.211 g/cm(3) and 0.228 g/cm(3), respectively. We extrapolate experimental vapour pressu re data by use of Antoine's law to the temperature range covered by simulat ion and yield good agreement between simulation and experiment. We note tha t the vapour pressure in simulation is essentially governed by the ideal va pour pressure. (C) 1999 Elsevier Science B.V. All rights reserved.