DIRECT INDICATION OF THE LIQUID GAS REGION IN LENNARD-JONES SYSTEMS BY CONVENTIONAL MOLECULAR-DYNAMICS CALCULATIONS

We demonstrate the occurrence of coexisting gas and liquid phases in the Lennard-Jones (LJ) system by direct evidence using conventional molecular dynamics calculations (MDC) for the NVEp ensemble. The computations require only evaluation of nearest neighbor distributions in the N-particle system. The results are practically independent of the potential cutoff and the number of particles used for the MDC. While the coexistence region of the LJ system can be detected reliably for densities outside the neighborhood of the critical point, reliable determination of the critical point poses problems. However, this disadvantage cannot be avoided by any other method using model calculations with a finite number of particles.