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

Abstract

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 Zerón et al.

GRAPHICAL ABSTRACT

Keywords:

• Square-well fluid
• Monte Carlo
• molecular dynamics
• critical point
• vapour-liquid coexistence

Acknowledgments

We also acknowledge the Centro de Supercomputación de Galicia (CESGA, Santiago de Compostela, Spain) for providing access to computing facilities. FS is very grateful with the Universidad de Huelva for its hospitality on his sabbatical leave.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Consejo Nacional de Ciencia y Tecnología (CONACyT) (México) [grant number CB-2017-2018-A1-S-30736-F-2164], Ministerio de Ciencia e Innovación [grant number PID2021-125081NB-I00], Junta de Andalucía [grant number. P20-00363], and Universidad de Huelva [grant numbers  P.O. FEDER UHU-1255522 and FEDER-UHU-202034], the last four cofinanced by EU FEDER funds.