Accurate effective potentials and virial coefficients in real fluids Part IV. Heterodiatomic and polyatomic substances with permanent multipoles and their mixtures with noble gases

Ramos, J. Eloy; Rı́o, Fernando del; McLure, Ian A.

doi:10.1039/b103003p

Cited by 18 publications

(5 citation statements)

References 24 publications

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“…The reference potential is recovered at s = 1. It has been shown to provide an excellent approximation for many gases [41][42][43][44] . Furthermore, it has an analytical expression for the second virial coefficient.…”

Section: New Cg Parameterizationsmentioning

confidence: 99%

Non-conformal coarse-grained potentials for water

Rodríguez-López

Khalak

Karttunen

2017

The Journal of Chemical Physics

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Water is a notoriously difficult substance to model both accurately and efficiently. Here, we focus on descriptions with a single coarse-grained particle per molecule using the so-called Approximate Non-Conformal (ANC) and generalized Stockmayer potentials as the starting points. They are fitted using the radial distribution function and the liquid-gas density profile of the atomistic SPC/E model by downhill simplex optimization. We compare the results with monatomic water (mW), ELBA, as well as with direct Iterative Boltzmann Inversion (IBI) of SPC/E. The results show that symmetrical potentials result in non-transferable models, that is, they need to be reparametrized for new state-points. This indicates that transferability may require more complex models. Furthermore, the results also show that the addition of a point dipole is not sufficient to make the potentials accurate and transferable to different temperatures (300 K-500 K) and pressures without an appropriate choice of properties as targets during model optimization.

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Section: New Cg Parameterizationsmentioning

confidence: 99%

Non-conformal coarse-grained potentials for water

Rodríguez-López

Khalak

Karttunen

2017

The Journal of Chemical Physics

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“…In this section we develop the ANC+ATM model and specify the main assumptions made in it. As a first approximation, ANC potentials are used to represent the two-body interactions because they reproduce very accurately the experimental data for the second virial coefficient B exp (T ) of the substances studied [38][39][40][41]. As the ANC family includes potential profiles with different degrees of softness, a particular ANC interaction is determined by three molecular parameters: the depth (ε) and position (δ) of the potential well, and the softness (s) of the potential profile [42,43]; its functional form corresponds to a modified Kihara potential…”

Section: Anc+atm Model Of the Third Virial Coefficientmentioning

confidence: 99%

“…Parameters of intermolecular potentials used in this work. Two-body parameters were taken from [38][39][40][41], with the exception of the acoustic set of argon [48] (second entry for Ar). The ATM coefficient ν was taken from the indicated references, or approximated [43] when no reference is given.…”

Section: Anc+atm Model Of the Third Virial Coefficientmentioning

confidence: 99%

“…This property makes ANC potentials particularly well suited for the systematic determination of (effective) binary interaction potentials. The values of the interaction parameters ε, δ and s have been determined with high precision by inversion of experimental data B exp (T ) for many substances; the values for all the fluids under study were determined by McLure et al [38][39][40][41] and are reproduced in table 1.…”

Section: Anc+atm Model Of the Third Virial Coefficientmentioning

confidence: 99%

“…We expect (31) to deteriorate as an approximation when s is decreased much below 0.55, because the parametric plots for ethane and propane already show a slight curvature. On the other hand, cases with s > 1 are not problematic because molecules that soft are quite uncommon [38][39][40][41]. It is worth mentioning that ( 31)- (33) imply that the effect of ternary forces is stronger for softer molecules.…”

Section: Anc+atm Model Of the Third Virial Coefficientmentioning

confidence: 99%

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Third virial coefficient of nonpolar gases from accurate binary potentials and ternary forces

Guzmán¹,

Rı́o²

2007

J. Phys. B: At. Mol. Opt. Phys.

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An explicit model for the third virial coefficient C(T) is presented, based on accurate binary interactions plus three-body forces; its predictions are compared to experimental data for 15 fluids (argon, krypton, xenon, nitrogen, oxygen, fluorine, carbon monoxide, carbon dioxide, perfluoromethane, methane, ethene, ethane, propane, n-butane, and n-pentane). Three-body interactions are represented by the Axilrod–Teller–Muto (ATM) triple-dipole potential, while the binary potential profile is systematically varied using approximate non-conformal (ANC) potentials. Non-conformality affects significantly both two- and three-body contributions to C(T). A formula for C(T) of ANC+ATM systems is obtained in terms of all interaction parameters; the three-body contribution is proportional to the parameter ν of the ATM potential while its temperature dependence is proportional to that of a reference fluid (argon). The ANC+ATM model reproduces C(T) within experimental error for most of the fluids considered, with a small negative deviation in some cases, which may be ascribed to the need of a complement to the ATM term.

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