Molecular modeling of the liquid-vapor interfaces of a multi-component mixture: Prediction of the coexisting densities and surface tensions at different pressures and gas compositions

Abstract

Two-phase molecular simulations are performed in order to report the interfacial tensions and the coexisting densities of a multicomponent mixture (nitrogen + methane) + water for five gas compositions in the pressure range of 1-30 MPa at 298 K. The interfacial tensions are calculated using different definitions and the long range corrections of the surface tensions are considered using expressions designed for multicomponent mixtures and each definitions. We can conclude that the agreement with experiments is quantitative with deviations smaller than 5% for the interfacial tensions and 2% for the densities. The interfacial region is described in terms of specific arrangements of the gas components at the water surface. © 2013 AIP Publishing LLC. [http://dx

Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

“…Differences between calculations obtained using Eqs. (14) and (15) decrease as the cutoff distance is larger, as previously explained. In particular, the tangential pressure at the liquid phase passes from 0.3 to 0.2 when the cutoff distance increases.…”

“…4(c) shows the difference between both components of the pressure tensor, P N (z) − P T (z), as a function of z for the systems considered, including the use of different cutoff distances and Eqs. (14) and (15). Surprisingly, calculations obtained from Eq.…”

“…Exceptions to this rule in the literature are the works of Chapela, Alejandre and co-workers, [10][11][12][13] and Malfreyt and co-workers. 14,15 The new generation of alternative methods for determining the surface tension and the components of the pressure tensor constitute a collection of effective and elegant techniques based on the thermodynamic definition of these properties. Consider a system in which the number of particles, N, the volume V , and temperature T are constant.…”

“…This approach corresponds to perturbative approaches such as the Test-Area (TA) technique 3 for the surface tension and the Volume Perturbation (VP) methods for the determination of the macroscopic components of the pressure tensor. [16][17][18] These methods are becoming very popular and are being used routinely to determine the vapour-liquid interfacial properties of Lennard-Jones (LJ), 7,[19][20][21] several models of water, 22,23 the Mie potential, 24 binary mixtures, [25][26][27] or real systems 15,[28][29][30][31][32][33] among others.…”

Determination of interfacial tension of binary mixtures from perturbative approaches

“…Examples of these methods are the Test-Area (TA) technique of Gloor et al [3], the Volume Perturbation (VP) method of de Miguel and Jackson [9][10][11], the Wandering Interface Method (WIM), introduced by MacDowell and Bryk [12], and the use of the Expanded Ensemble (EE), based on the original work of Lyuvartsev et al [13], for calculating the surface tension proposed independently by Errington and Kofke [14] and de Miguel [15]. These methods are becoming very popular and are being used routinely to determine the vapour-liquid interfacial properties of different potential model fluids [7,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”