Comprehensive study of the vapour–liquid equilibria of the pure two-centre Lennard–Jones plus pointquadrupole fluid

Results of a systematic investigation of the vapour–liquid equilibria (VLE) of 30 individual two-centre Lennard–Jones plus pointquadrupole model fluids (2CLJQ) are reported over a range of reduced quadrupolar momentum 0≤Q∗2≤4 and of reduced elongation 0≤L∗≤0.8. Temperatures investigated are from about 55 to about 95% of the critical temperature of each fluid. Uniformly, the NpT+test particle method (NpT+TP method) based on molecular dynamics simulations is used for the generation of vapour pressures, saturated densities, and saturated enthalpies. Critical temperatures Tc∗ and densities ρc∗ are obtained from Guggenheim’s equations. Empirical correlations for critical data Tc∗ and ρc∗ as well as for saturated densities ρ′∗, ρ″∗, and vapour pressures pσ∗ are developed as global functions of the model parameters. In most cases they describe the simulation data within their statistical uncertainties. Critical pressures and acentric factors of the 2CLJQ fluid can be calculated from the correlations. The present simulations are a sound basis for adjustments of the model parameters Q∗2, L∗, σ, and ϵ to experimental VLE data of real fluids.