Computation of thermodynamic properties in the continuous fractional component Monte Carlo Gibbs ensemble

Computation of thermodynamic properties in the continuous fractional component Monte Carlo Gibbs ensemble

Poursaeidesfahani, A. (TU Delft Engineering Thermodynamics)
Rahbari, A. (TU Delft Engineering Thermodynamics)
Torres-Knoop, Ariana (Universiteit van Amsterdam)
Dubbeldam, D. (Universiteit van Amsterdam)
Vlugt, T.J.H. (TU Delft Engineering Thermodynamics)

2017

It is shown that ensemble averages computed in the Gibbs Ensemble with Continuous Fractional Component Monte Carlo (CFCMC GE) are different from those computed in the conventional Gibbs Ensemble (GE). However, it is possible to compute averages corresponding to the conventional GE while performing simulations in the CFCMC GE. In this way, one can benefit from the nice features of CFCMC GE (e.g. more efficient particle exchange) and at the same time compute the ensemble averages that correspond to the conventional GE. As a case study, the equilibrium pressure and densities of the systems of 256 and 512 LJ particles at different reduced temperatures ((Formula presented.)) are computed in the conventional GE and CFCMC GE. The validity of the expressions derived for computation of the thermodynamic pressure and densities corresponding to the conventional GE and computed in the CFCMC GE is examined numerically. The thermodynamic pressure in the conventional GE and CFCMC GE typically differs by at most 4%. It is shown that a very good estimate of the average pressure and densities corresponding to the conventional GE can be obtained by performing simulation in CFCMC GE and ignoring the contributions of the fractional molecule. It is also shown that the fractional molecule does not have an influence on the structure of the liquid, even for very small system sizes (e.g. 40 particles). The approach used here to compute the equilibrium pressure and densities of the conventional GE using the CFCMC GE can be easily extended to other thermodynamic properties and other ensembles.

Continuous fractional component Monte Carlo
Gibbs ensemble
thermodynamic properties
vapour–liquid equilbria

http://resolver.tudelft.nl/uuid:e23aaaf8-a2a4-4363-82f9-ba407cab1101

https://doi.org/10.1080/08927022.2016.1244607

2017-12-12

0892-7022

Molecular Simulation, 43 (3), 189-195

Accepted Author Manuscript

Institutional Repository

journal article

© 2017 A. Poursaeidesfahani, A. Rahbari, Ariana Torres-Knoop, D. Dubbeldam, T.J.H. Vlugt