Developing optimal Wertheim-like models of water for use in Statistical Associating Fluid Theory (SAFT) and related approaches

Clark, Gary F.; Haslam, Andrew J.; Galindo, Amparo; Jackson, George

doi:10.1080/00268970601081475

Cited by 184 publications

(269 citation statements)

References 145 publications

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“…The contribution of dispersive forces to the properties can be obtained either using a mean field approach, or eventually modifying the Kolafa Nezbeda model so that one has a LJ center plus four associating sites. 64,65 This is a reasonable model of water, and has been shown that when used in combination with SAFT it can describe many properties of water. Thus SAFT provides a good description of water because the potential used to describe water (i.e the PES) is simple but still reasonable.…”

Section: Bmentioning

confidence: 99%

Water: one molecule, two surfaces, one mistake

Vega

2015

Molecular Physics

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In order to rigorously evaluate the energy and dipole moment of a certain configuration of molecules one needs to solve the Schrödinger equation. Repeating this for many different configurations allows one to determine the potential energy surface (PES) and the dipole moment surface (DMS). Since the early days of computer simulation it has been implicitly accepted that for empirical potentials the charges used to fit the PES should also be used to describe the DMS. This is a mistake. Partial charges are not observable magnitudes. They should be regarded as adjustable fitting parameters. Optimal values used to describe the PES are not necessarily the best to describe the DMS. One could use two fits: one for the PES, and another for the DMS. This is a common practice in the quantum chemistry community, but not used so often by the community performing computer simulations. This idea affects all types of modelling of water (with the exception of ab-initio calculations) from coarse grained to non-polarizable and polarizable models.We anticipate that an area that will benefit dramatically from having both, a good PES and a good DMS, is the modelling of water in the presence of electric fields.

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Section: Bmentioning

confidence: 99%

Water: one molecule, two surfaces, one mistake

Vega

2015

Molecular Physics

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“…63,77 At one side, this is a reasonable approach, since the parameters of such equations of state are rather degenerated and the standard optimization on the pure component equilibrium data only can provide several different parameter sets. On the other hand, since the model is not able to describe correctly the structure at molecular level, the associating parameters may depend on the choice of simulated property taken into account.…”

Section: Figmentioning

confidence: 99%

Size distribution of associated clusters in liquid alcohols: Interpretation of simulation results in the frame of SAFT approach

Janeček

Paricaud

2013

The Journal of Chemical Physics

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The size distribution and topology of associated clusters for primary alcohols is studied using molecular dynamics simulations. Liquid ethanol, propanol, butanol, hexanol, and octanol are simulated at pressure P = 1 bar and temperatures T = 300 K, T = 350 K, and T = 400 K. The fractions of molecules with different sets of hydrogen bonded partners, the size of associated cluster and the site-site distribution functions between atoms participating on hydrogen bonding are extracted from simulated trajectories. For all alcohols longer than ethanol, the length of the alkyl chain has only a marginal effect on the association. Consequently, related properties like coordination numbers of hydroxyl group, size distribution of associates, or fractions of differently coordinated alcohol molecules are independent on the molecular size. Although we employed a force-field without involved polarizability, we observe a positive cooperativity of hydrogen bonding simply as a consequence of steric and electrostatic interactions. The size and topology of associates is analyzed within the frame of 3B model of statistical association fluid theory. Although this approach enables good thermodynamic description of systems containing associating compounds, several insufficiencies appear in the description at molecular level. © 2013 AIP Publishing LLC.[http://dx.doi.org/10.1063/1.4827107]

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“…It is assumed that a site can bond only once; this assumption has worked well in the past for water and alcohol. 55,56 It is calculated as the geometric mean of the value at r 1 and r 2…”

Section: B Isaft Density Functional Theorymentioning

confidence: 99%

Hydrophobic and hydrophilic interactions in aqueous mixtures of alcohols at a hydrophobic surface

Ballal

Chapman

2013

The Journal of Chemical Physics

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Aqueous solutions of alcohols are interesting because of their anomalous behavior that is believed to be due to the molecular structuring of water and alcohol around each other in solution. The interfacial structuring and properties are significant for application in alcohol purification processes and biomolecular structure. Here we study aqueous mixtures of short alcohols (methanol, ethanol, 1-propanol, and 2-propanol) at a hydrophobic surface using interfacial statistical associating fluid theory which is a perturbation density functional theory. The addition of a small amount of alcohol decreases the interfacial tension of water drastically. This trend in interfacial tension can be explained by the structure of water and alcohol next to the surface. The hydrophobic group of an added alcohol preferentially goes to the surface preserving the structure of water in the bulk. For a given bulk alcohol concentration, water mixed with the different alcohols has different interfacial tensions with propanol having a lower interfacial tension than methanol and ethanol. 2-propanol is not as effective in decreasing the interfacial tension as 1-propanol because it partitions poorly to the surface due to its larger excluded volume. But for a given surface alcohol mole fraction, all the alcohol mixtures give similar values for interfacial tension. For separation of alcohol from water, methods that take advantage of the high surface mole fraction of alcohol have advantages compared to separation using the vapor in equilibrium with a water-alcohol liquid. © 2013 AIP Publishing LLC.

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Developing optimal Wertheim-like models of water for use in Statistical Associating Fluid Theory (SAFT) and related approaches

Cited by 184 publications

References 145 publications

Water: one molecule, two surfaces, one mistake

Water: one molecule, two surfaces, one mistake

Size distribution of associated clusters in liquid alcohols: Interpretation of simulation results in the frame of SAFT approach

Hydrophobic and hydrophilic interactions in aqueous mixtures of alcohols at a hydrophobic surface

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