Composition dependence of thermodynamic, dynamic and dielectric properties of water–methanol model mixtures. Molecular dynamics simulation results with the OPLS-AA model for methanol

Galicia‐Andrés, Edgar; Domínguez, Héctor; Pusztai, László; Pizio, Orest

doi:10.1016/j.molliq.2015.08.061

Cited by 35 publications

(23 citation statements)

References 44 publications

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“…where the upper limit of integration in this equation is taken to correspond to the first minimum r min of 13602-5 the pair distribution function g i j (r) of the species i and j. A detailed description of the behavior of this property, for a set of models related to the present study, was given in [2,3,43]. Very recent reports also concern the evolution of the first coordination numbers, see, e.g., figure 7 of reference [8] and figures 24 and 25 of reference [9].…”

Section: Resultsmentioning

confidence: 99%

Molecular dynamics simulations of the properties of water-methanol mixtures. Effects of force fields

Sánchez¹,

Domínguez²,

Pizio³

2019

Condens. Matter Phys.

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Isothermal-isobaric molecular dynamics simulations are used to examine the microscopic structure and some properties of water-methanol liquid mixture. The TIP4P/2005 and SPC/E water models are combined with the united atom TraPPE and the all-atom force field model for methanol. Our principal focus is to evaluate the quality of predictions of different combinations of model force fields concerning the composition dependence of basic properties of this system. Specifically, we explored the composition effects on density, excess molar volume and excess entropy, as well as on the surface tension and static dielectric constant. In addition, the structural properties are described in terms of the coordination numbers and the average number of hydrogen bonds between molecules of constituent species. Finally, the composition dependence of self-diffusion coefficients of the species is evaluated. All theoretical predictions are tested with respect to experimental data.

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Section: Resultsmentioning

confidence: 99%

Molecular dynamics simulations of the properties of water-methanol mixtures. Effects of force fields

Sánchez¹,

Domínguez²,

Pizio³

2019

Condens. Matter Phys.

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“…This is fully consistent with the observation of Weitkamp et al [16] concerning the structure of pure methanol at high (up to 0.9 GPa) pressures, who found that the structure factor changes as a response to pressure only at low momentum transfer values. (2) The most general trend with increasing pressure appeared to be the consistent shift of the position of the first maximum towards higher scattering variable values. (3) Pressure-induced intensity changes were more visible below a methanol content of about 50 mol%.…”

Section: Experimental Data: Total Scattering Structure Factorsmentioning

confidence: 93%

“…Methanol–water liquid mixtures at room temperature and atmospheric pressure are among the most extensively studied hydrogen-bonded liquids: recent experiments (e.g., [ 1 ]) and computer simulations (e.g., [ 2 , 3 ]) over the full concentration range are abound. Although quite a few studies have already appeared that considered the effect of temperature (e.g., [ 4 , 5 , 6 ]) on the structure of methanol–water liquid mixtures and the effect of pressure (e.g., [ 7 , 8 , 9 , 10 ]) on the structure of individual hydrogen-bonded liquids, a systematic study on the effect of high pressures is still missing.…”

Section: Introductionmentioning

confidence: 99%

Pressure-Dependent Structure of Methanol–Water Mixtures up to 1.2 GPa: Neutron Diffraction Experiments and Molecular Dynamics Simulations

et al. 2021

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Total scattering structure factors of per-deuterated methanol and heavy water, CD3OD and D2O, have been determined across the entire composition range as a function of pressure up to 1.2 GPa, by neutron diffraction. The largest variations due to increasing pressure were observed below a scattering variable value of 5 Å−1, mostly as shifts in terms of the positions of the first and second maxima. Molecular dynamics computer simulations, using combinations of all-atom potentials for methanol and various water force fields, were conducted at the experimental pressures with the aim of interpreting neutron diffraction results. The peak-position shifts mentioned above could be qualitatively reproduced by simulations, although in terms of peak intensities, the accord between neutron diffraction and molecular dynamics was much less satisfactory. However, bearing in mind that increasing pressure must have a profound effect on repulsive forces between neighboring molecules, the agreement between experiment and computer simulation can certainly be termed as satisfactory. In order to reveal the influence of changing pressure on local intermolecular structure in these “simplest of complex” hydrogen-bonded liquid mixtures, simulated structures were analyzed in terms of hydrogen bond-related partial radial distribution functions and size distributions of hydrogen-bonded cyclic entities. Distinct differences between pressure-dependent structures of water-rich and methanol-rich composition regions were revealed.

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“…Molecules in pure methanol form open, non-linear chains with approximately tetrahedral coordination that are either hexa-and/or octamer molecular clusters due to the intermolecular hydrogen bonding [34,35]. The thermodynamic values of water-methanol solutions vary from what would be expected after the mixing of these two liquids [35][36][37][38][39]. Even a small amount of methanol causes a change in the water molecules' arrangement through the introduction of hydrophobic methyl groups [39].…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Methanol–Water Interaction on the Surface Layer on Titanium in CH3OH-H2O-LiClO4 Solutions

2020

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The purpose of this study was to explain the mechanism of formation and to examine the composition of the anodic film formed on the surface of titanium in an anhydrous neutral methanol solution of electrolytes. In an environment deprived of water molecules, the growth of a 3D-phase titanium oxide layer is not possible. Electrochemical investigations demonstrated that the Ti surface in CH3OH-LiClO4 solutions experienced a pseudo-passivation with the formation of a methoxy layer, which resulted from the reaction of the metal surface with alcohol molecules. The presence of this methoxy surface film was confirmed through XPS and in situ FTIR measurements. The layer blocked the Ti anodic dissolution at the potential range corresponding to the stability of methanol and methoxy ions (i.e., <0.55 V). At potentials over 0.55 V, the methoxy layer was oxidised, which caused the “depassivation” of the metal surface and the etching of titanium. The addition of water changed the properties of Ti in CH3OH-LiClO4 solutions, but only with a water content above 0.2 mole fraction. Below this concentration of water, titanium behaved like it would in an anhydrous solution of methanol. In the range of water concentration of 0.2 to 0.7 mole fraction, the structure of the solution is strengthened because both components of the solvent formed separate percolating networks. The strengthening of the solution structure resulted in a strengthening of the surface layer of Ti(OH)m(OCH3)n. Such a layer had strong barrier properties similar to the properties of an organic polymer film. The formation and growth of a stable layer of TiO2 were possible only in a solvent when the water concentration was higher than ≈0.7 mole fraction.

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Composition dependence of thermodynamic, dynamic and dielectric properties of water–methanol model mixtures. Molecular dynamics simulation results with the OPLS-AA model for methanol

Cited by 35 publications

References 44 publications

Molecular dynamics simulations of the properties of water-methanol mixtures. Effects of force fields

Molecular dynamics simulations of the properties of water-methanol mixtures. Effects of force fields

Pressure-Dependent Structure of Methanol–Water Mixtures up to 1.2 GPa: Neutron Diffraction Experiments and Molecular Dynamics Simulations

The Effect of the Methanol–Water Interaction on the Surface Layer on Titanium in CH3OH-H2O-LiClO4 Solutions

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