Molecular simulations of the vapour-liquid coexistence curve of square-well dimer fluids

In this work, we evaluate the liquid-vapour coexistence diagram and the critical point for two different ranges, lambda = 1.5 and 2.0 sigma of the square-well dimer fluid, using two different simulation methods: (1) In the critical point vicinity, we use a new algorithm, based on transition rates, that can obtain the chemical potential as a function of the density at a given temperature and (2) Molecular Dynamics simulations using the direct coexistence technique for temperatures far below the critical region. The transition rate method has been proposed by Sastre and was used for the evaluation of the critical temperature of square-well monomers with high accuracy. The simulations in the low-temperature region were carried out using molecular dynamics simulations with the direct coexistence method and a continuous version of the square-well potential proposed recently by Zeron et al.

Automated summary

In this work, two different simulation methods were used to evaluate the liquid-vapour coexistence diagram and the critical point for the square-well dimer fluid. A new algorithm based on transition rates was employed to obtain the chemical potential as a function of density near the critical point, and molecular dynamics simulations using the direct coexistence technique were conducted at low temperatures. The results were compared with the previous studies on square-well monomers and a recent proposal of a continuous version of the square-well potential.