Molecular Modeling of Thiophene in the Vapor–Liquid Equilibrium

Juárez‐Guerra, Francisco M.; Rivera, Juan; Zúñiga‐Moreno, Abel; Galicia‐Luna, Luis A.; Rico, José Luis; Lara, J.

doi:10.1080/01496390500446129

Cited by 15 publications

(18 citation statements)

References 43 publications

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“…3. The averages corresponding to bulk densities of water and thiophene at the water/air and water/thiophene interfaces are 1.004 and 1.048 (g/cm 3 ), in agreement with the experimental values of 0.997 and 1.052 (g/cm 3 ), 50 respectively. The oxygen and hydrogen atoms of water have almost identical profiles at both interfaces with air and thiophene.…”

Section: A Local Density Profilessupporting

confidence: 86%

“…Analysis of the present simulations also demonstrates the presence of strong density oscillations in the thiophene near the aluminium surface while this phenomenon is not observed at the thiophene/air interface. The density of thiophene varies from 1.17 g/cm 3 at z = −5 Å to 0.904 g/cm 3 at z = 10 Å with the average value in this region of 1.051 g/cm 3 , comparing well with the experimental value of 1.052 g/cm 3 at 303 K. 50 Around z = 0, the density of thiophene is roughly flat as expected for a liquid/air interface despite the pressure of the aluminium wall. This allows us to consider that the constraint to get the slab geometry has no prejudicial influence on the thiophene/air interface.…”

Section: A Local Density Profilessupporting

confidence: 79%

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Analysis of the second harmonic generation signal from a liquid/air and liquid/liquid interface

Pham

Jonchère

Dufrêche

et al. 2017

The Journal of Chemical Physics

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Three different liquid interfaces, water/air, thiophene/air, and water/thiophene, were probed using the second harmonic generation (SHG) technique. Thiophene and water have been chosen because the hyperpolarizability of these molecules has already been measured or calculated and the different values can be found in literature. We have studied the microscopic structure of these interfaces by comparing the components of the second order susceptibility tensor determined from the SHG polarization curve analysis with those determined via a molecular dynamics (MD) simulation of these interfaces. We have indeed computed the structure and orientation of water and thiophene molecules at the liquid/air and liquid/liquid (L/L) interfaces as a function of the distance from the interface. The integrated susceptibility values calculated by MD simulations agree well with SHG results and validate the choice of force fields that should permit to quantify more complex L/L interfaces.

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Section: A Local Density Profilessupporting

confidence: 86%

Section: A Local Density Profilessupporting

confidence: 79%

Analysis of the second harmonic generation signal from a liquid/air and liquid/liquid interface

Pham

Jonchère

Dufrêche

et al. 2017

The Journal of Chemical Physics

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“…MD simulations allow the study of systems under phase equilibrium and specifically can be applied to examine the contributions due to intramolecular and intermolecular interactions to the thermophysical properties directly at the equilibrium interface and also at their corresponding bulk phases [10][11][12][13][14]. The simulation of the coexisting VLE uses pair-effective intermolecular potentials that are capable of reproducing their thermophysical properties [7,15,16] and transport properties for simple fluids [17][18][19].…”

Section: Methodsmentioning

confidence: 99%

The Intramolecular Pressure and the Extension of the Critical Point’s Influence Zone on the Order Parameter

Rivera

Nicanor-Guzman

Guerra-González

2015

Advances in Condensed Matter Physics

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The critical point affects the coexistence behavior of the vapor-liquid equilibrium densities. The length of the critical influence zone is under debate because for some properties, like shear viscosity, the extension is only a few degrees, while for others, such as the density order parameter, the critical influence zone covers up to hundreds of degrees below the critical temperature. Here we show that, for ethane, the experimental critical influence zone covers a wide zone of tens of degrees (below the critical temperature) down to a transition temperature, at which the apparent critical influence zone vanishes, and the transition temperature can be predicted through a pressure analysis of the coexisting bulk liquid phase, using a simple molecular potential. The liquid phases within the apparent critical influence zone show low densities, making them behave internally like their corresponding vapor phases. Therefore, Molecular Dynamics simulations reveal that the experimentally observed wide extension of the critical influence zone is the result of a vapor-like effect due to low bulk liquid phase densities.

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“…We use the MD methodology to simulate the vacuumliquid equilibrium ͑VLE͒ of water at 298.15 K. This methodology has been employed in previous works to study the bulk and interfacial properties of systems in vapor-liquid equilibrium, including polar, [17][18][19] nonpolar, 20 and their mixtures. [21][22][23] We integrate the equations of motion using the Gear fourth-order predictor-corrector algorithm with a time step of 1 fs, and control the temperature using the Gaussian isokinetic thermostat 24,25 and the Evans-Murad quaternion formalism.…”

Section: ͑6͒mentioning

confidence: 99%

Polarizable contributions to the surface tension of liquid water

Rivera

Starr

Paricaud

et al. 2006

The Journal of Chemical Physics

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Surface tension, ␥, strongly affects interfacial properties in fluids. The degree to which polarizability affects ␥ in water is thus far not well established. To address this situation, we carry out molecular dynamics simulations to study the interfacial forces acting on a slab of liquid water surrounded by vacuum using the Gaussian charge polarizable ͑GCP͒ model at 298.15 K. The GCP model incorporates both a fixed dipole due to Gaussian distributed charges and a polarizable dipole. We find a well-defined bulklike region forms with a width of Ϸ31 Å. The average density of the bulklike region agrees with the experimental value of 0.997 g / cm 3 . However, we find that the orientation of the molecules in the bulklike region is strongly influenced by the interfaces, even at a distance five molecular diameters from the interface. Specifically, the orientations of both the permanent and induced dipoles show a preferred orientation parallel to the interface. Near the interface, the preferred orientation of the dipoles becomes more pronounced and the average magnitude of the induced dipoles decreases monotonically. To quantify the degree to which molecular orientation affects ␥, we calculate the contributions to ␥ from permanent dipolar interactions, induced dipolar interactions, and dispersion forces. We find that the induced dipole interactions and the permanent dipole interactions, as well as the cross interactions, have positive contributions to ␥, and therefore contribute stability to the interface. The repulsive core interactions result in a negative contribution to ␥, which nearly cancels the positive contributions from the dipoles. The large negative core contributions to ␥ are the result of small oxygen-oxygen separation between molecules. These small separations occur due to the strong attractions between hydrogen and oxygen atoms. The final predicted value for ␥ ͑68.65 mN/ m͒ shows a deviation of Ϸ4% of the experimental value of 71.972 mN/ m. The inclusion of polarization is critical for this model to produce an accurate value.

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Molecular Modeling of Thiophene in the Vapor–Liquid Equilibrium

Cited by 15 publications

References 43 publications

Analysis of the second harmonic generation signal from a liquid/air and liquid/liquid interface

Analysis of the second harmonic generation signal from a liquid/air and liquid/liquid interface

The Intramolecular Pressure and the Extension of the Critical Point’s Influence Zone on the Order Parameter

Polarizable contributions to the surface tension of liquid water

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