Phase diagram of the modified Lennard-Jones system

An investigation of the precise determination of melting temperature in the modified Lennard-Jones system under pressure-free conditions [Y. Asano and K. Fuchizaki, J. Phys. Soc. Jpn. 78, 055002 (2009)] was extended under finite-pressure conditions to obtain the phase diagram. The temperature and pressure of the triple point were estimated to be 0.61 epsilon/k(B) and 0.0018(5) epsilon/sigma(3), and those of the critical point were 1.0709(19) epsilon/k(B) and 0.1228(20) epsilon/sigma(3), where epsilon and sigma are the Lennard-Jones parameters for energy and length scales, respectively, and k(B) is the Boltzmann constant. The potential used here has a finite attractive tail and does not suffer from cutoff problems. The potential can thus be a useful standard in examining statistical-mechanical problems in which different treatments for the tail would lead to different conclusions. The present phase diagram will then be a useful guide not only for equilibrium calculations but also for nonequilibrium problems such as discussions of the limits of phase (in)stability. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4764855]