Molecular‐Based Modeling of Water and Aqueous Solutions at Supercritical Conditions

Chialvo, Ariel A.; Cummings, Peter T.

doi:10.1002/9780470141687.ch3

Cited by 76 publications

(35 citation statements)

References 295 publications

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“…This geometric measure is broadly consistent with the degree of HB determined using an alternative energetic definition: n HB ∼ 1.7 at 298 K, 0.958 g cm −3 , and 0.101 MPa (see reference [198]) and n HB ∼ 1.8 at 298 K, 1.006 g cm −3 , and 0.1 MPa (see reference [199]). Both Kalinichev and Bass [200] and Chialvo and Cummings [201] have concluded that the geometric definition proposed by Mountain successfully represents the degree of HB in the system under normal conditions (away from the critical region). Kalinichev and Table 3 using the association kernels based on the LJ (green dashed curve) and Mie (red continuous curve) RDFs (colour online).…”

Section: Watermentioning

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: Watermentioning

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 the short-ranged interactions, the cutoff radius was set to 1.2 nm. Both energy and pressure tail corrections [62] have been applied to the standard 12-6 LJ potential for the bulk MD simulations. The long range electrostatic interactions were calculated using the particle mesh Ewald (PME) summation [63] with the tinfoil boundary condition (infinite dielectric) and a FFT grid spacing of 0.12 nm.…”

Section: Eqtmentioning

confidence: 99%

Extended coarse-grained dipole model for polar liquids: Application to bulk and confined water

2018

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We report a multiscale investigation of water inside graphene slit-like channels that extends from the detailed all-atom level (AA) to the cheaper particle-based coarse-grained (CG) level, and to the continuum-based level. Since water is a highly polar solvent, the detailed description of its structural and dielectric properties close to the interfaces is of paramount importance in many applications. For this purpose, we have systematically developed an extended dipole-based CG model using the relative entropy method that can accurately reproduce the radial distribution function (RDF), diffusion coefficient, and bulk dielectric permittivity of the underlying AA reference model. The extended model is simple yet complex enough to shed light on the role of dipolar interactions in polar liquids such as water. Using the CG potentials developed in this work, we show that the structure, parallel dielectric permittivity, and polarization profiles can be captured reasonably well compared to all-atom molecular dynamics (AAMD) simulations. Furthermore, we use the empirical potential-based quasi-continuum (EQT) framework to predict the density and polarization of water molecules inside nano slit channels of various widths. Our continuum analyses reveal that the mean-field treatment of dipolar correlations in combination with the use of CG potentials are sufficient to accurately reproduce the structural variations of water inside the confined graphene slit channels. Finally, by using coarse-grained molecular dynamics (CGMD) and EQT simulations, we comment on the applicability of dipolar-based CG models in reproducing the structure of water near charged interfaces.

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“…Correspondingly, SCW is broken into discontinuous fragments, i.e. , dimers and small clusters [ 83 ]. Because of the high difficulty in conducting measurements under supercritical conditions, the exact structural motif for SCW and corresponding evolutionary process with temperature are still far from being completely acquainted, which necessitates the researches on the long-range order and rearrangement dynamics of HB.…”

Section: Water Structure Changes With Temperaturementioning

confidence: 99%

Changes of Water Hydrogen Bond Network with Different Externalities

Zhao

Yang

2015

IJMS

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It is crucial to uncover the mystery of water cluster and structural motif to have an insight into the abundant anomalies bound to water. In this context, the analysis of influence factors is an alternative way to shed light on the nature of water clusters. Water structure has been tentatively explained within different frameworks of structural models. Based on comprehensive analysis and summary of the studies on the response of water to four externalities (i.e., temperature, pressure, solutes and external fields), the changing trends of water structure and a deduced intrinsic structural motif are put forward in this work. The variations in physicochemical and biological effects of water induced by each externality are also discussed to emphasize the role of water in our daily life. On this basis, the underlying problems that need to be further studied are formulated by pointing out the limitations attached to current study techniques and to outline prominent studies that have come up recently.

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Molecular‐Based Modeling of Water and Aqueous Solutions at Supercritical Conditions

Cited by 76 publications

References 295 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

Extended coarse-grained dipole model for polar liquids: Application to bulk and confined water

Changes of Water Hydrogen Bond Network with Different Externalities

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