Theory and computer simulations of heteronuclear diatomic hard-sphere molecules (hard dumbbells)

Archer, Amanda L.; Jackson, George

doi:10.1080/00268979100101631

Cited by 73 publications

(20 citation statements)

References 32 publications

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“…The Wertheim TPT1 treatment therefore provides a route to the separate contributions to the EOS for both reversible association (e.g., resulting from intermolecular HB) and for molecules formed from bonded segments. A consideration of mixtures of associating monomers can also be employed to provide a reliable description of the thermodynamic properties of heteronuclear dimers [59,60], trimers [61,62], and generic molecules formed from segments of different type [55,[62][63][64][65][66][67][68][69][70][71]; such a formalism has been invaluable in the recent development of group-contribution approaches for heteronuclear molecules based on the SAFT EOS, allowing for the separate chemical moieties to be considered explicitly [72][73][74][75][76][77][78].…”

Section: Introductionmentioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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(2015) The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids, Molecular Physics, 113:9-10, 948-984, DOI: 10.1080/00268976.2015 An accurate representation of molecular association is a vital ingredient of advanced equations of state (EOSs), providing a description of thermodynamic properties of complex fluids where hydrogen bonding plays an important role. The combination of the first-order thermodynamic perturbation theory (TPT1) of Wertheim for associating systems with an accurate description of the structural and thermodynamic properties of the monomer fluid forms the basis of the statistical associating fluid theory (SAFT) family of EOSs. The contribution of association to the free energy in SAFT and related EOSs is very sensitive to the nature of intermolecular potential used to describe the monomers and, crucially, to the accuracy of the representation of the thermodynamic and structural properties. Here we develop an accurate description of the association contribution for use within the recently developed SAFT-VR Mie framework for chain molecules formed from segments interacting through a Mie potential [T. Lafitte, A. Apostolakou, C. Avendaño, A, Galindo, C. S. Adjiman, E. A. Müller, and G. Jackson, J. Chem. Phys. 139, 154504 (2013)]. As the Mie interaction represents a soft-core potential model, a method similar to that adopted for the Lennard-Jones potential [E. A. Müller and K. E. Gubbins, Ind. Eng. Chem. Res. 34, 3662 (1995)] is employed to describe the association contribution to the Helmholtz free energy. The radial distribution function (RDF) of the Mie fluid (which is required for the evaluation of the integral at the heart of the association term) is determined for a broad range of thermodynamic conditions (temperatures and densities) using the reference hyper-netted chain (RHNC) integral-equation theory. The numerical data for the association kernel of Mie fluids with different association geometries are then correlated for a range of thermodynamic states to obtain a general expression for the association contribution which can be applied for varying values of the Mie repulsive exponent. The resulting SAFT-VR Mie EOS allows for a much improved description of the vapour-liquid equilibria and single-phase properties of associating fluids such as water, methanol, ammonia, hydrogen sulphide, and their mixtures. A comparison is also made between the theoretical predictions of the degree of association for water and the extent of hydrogen bonding obtained from molecular simulations of the SPC/E and TIP4P/2005 atomistic models.

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Section: Introductionmentioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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“…For this we only need to build into the model equations of state for suitable reference systems. For example, a number of equations of state for short fused chains with asymmetric sites have been proposed 28,30,31 which could be incorporated to the model. This issue is being examined in more detail to arrive at definite recommendations.…”

Section: Extension To More Complex Systemsmentioning

confidence: 99%

Chemical potential and equations of state of hard core chain molecules

Escobedo

Pablo

1995

The Journal of Chemical Physics

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A novel approach is presented for the development of equations of state for chain molecules. The basic assumptions of the approach are supported by results of computer simulations of the chemical potential of athermal chains. Our model establishes a bridge between some elements of Wertheim's thermodynamic perturbation theory and the generalized Flory theory. New equations of state are presented for freely jointed tangent hard-sphere chains which are shown to be more accurate than other existing equations. Extensions of our approach are also presented for branched polymers and blends of polymers.

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“…Within the Wertheim TPT1 methodology [47][48][49][50][51][52][53] it is possible to develop formally, on the premise of a detailed heteronuclear molecular model, an equation of state maintaining a link between the nature of the different segments making up the molecules and the corresponding parameters. The first such studies of bonded heteronuclear models formed from hard-sphere segments included heteronuclear dimer, 54 linear triatomic, 55 and arbitrary polyatomic molecules. 56,57 Within the context of a SAFT treatment, several variants have been reformulated based on a heteronuclear tangent molecular model.…”

Section: Introductionmentioning

confidence: 99%

Group contribution methodology based on the statistical associating fluid theory for heteronuclear molecules formed from Mie segments

Papaioannou

Lafitte

Avendaño

et al. 2014

The Journal of Chemical Physics

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429

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A group contribution method for associating chain molecules based on the statistical associating fluid theory (SAFT-) The Journal of Chemical Physics 127, 234903 (2007) (2013)] is formulated within the framework of a group contribution approach (SAFT-γ Mie). Molecules are represented as comprising distinct functional (chemical) groups based on a fused heteronuclear molecular model, where the interactions between segments are described with the Mie (generalized Lennard-Jonesium) potential of variable attractive and repulsive range. A key feature of the new theory is the accurate description of the monomeric group-group interactions by application of a high-temperature perturbation expansion up to third order. The capabilities of the SAFT-γ Mie approach are exemplified by studying the thermodynamic properties of two chemical families, the n-alkanes and the n-alkyl esters, by developing parameters for the methyl, methylene, and carboxylate functional groups (CH 3 , CH 2 , and COO). The approach is shown to describe accurately the fluid-phase behavior of the compounds considered with absolute average deviations of 1.20% and 0.42% for the vapor pressure and saturated liquid density, respectively, which represents a clear improvement over other existing SAFT-based group contribution approaches. The use of Mie potentials to describe the group-group interaction is shown to allow accurate simultaneous descriptions of the fluid-phase behavior and second-order thermodynamic derivative properties of the pure fluids based on a single set of group parameters. Furthermore, the application of the perturbation expansion to third order for the description of the reference monomeric fluid improves the predictions of the theory for the fluid-phase behavior of pure components in the near-critical region. The predictive capabilities of the approach stem from its formulation within a group-contribution formalism: predictions of the fluid-phase behavior and thermodynamic derivative properties of compounds not included in the development of group parameters are demonstrated. The performance of the theory is also critically assessed with predictions of the fluid-phase behavior (vapor-liquid and liquid-liquid equilibria) and excess thermodynamic properties of a variety of binary mixtures, including polymer solutions, where very good agreement with the experimental data is seen, without the need for adjustable mixture parameters.

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Theory and computer simulations of heteronuclear diatomic hard-sphere molecules (hard dumbbells)

Cited by 73 publications

References 32 publications

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

Chemical potential and equations of state of hard core chain molecules

Group contribution methodology based on the statistical associating fluid theory for heteronuclear molecules formed from Mie segments

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