Table 6 - uploaded by Jadran Vrabec
Content may be subject to copyright.
Source publication
Molecular dynamics simulation results on hydrogen bonding in mixtures of methanol with CO2 at supercritical, liquid-like conditions are compared to 1H NMR spectroscopic data that have recently become available. The molecular models are parametrized using vapor-liquid equilibrium data only, which they reliably describe. A new molecular model for met...
Context in source publication
Similar publications
The surfactant shell stabilising the calcium cabonate core in overbased detergent additives of lubricant base oils was characterised
by computational and experimental methods, comprising classical force-field based molecular simulations and spin-probe Electron
Spin Resonance spectroscopy. An atomistic model is proposed for the detergents micelle st...
At strong first-order phase transitions, the entropy versus energy or, at constant pressure, enthalpy, exhibits convex behavior, and the statistical temperature curve correspondingly exhibits an S-loop or back-bending. In the canonical and isothermal-isobaric ensembles, with temperature as the control variable, the probability density functions bec...
Transport properties of liquid methanol and ethanol are predicted by molecular dynamics simulation. The molecular models for the alcohols are rigid, nonpolarizable, and of united-atom type. They were developed in preceding work using experimental vapor-liquid equilibrium data only. Self- and Maxwell-Stefan diffusion coefficients as well as the shea...
Multicomponent diffusion in liquids is ubiquitous in (bio)chemical processes. It has gained considerable and increasing interest as it is often the rate limiting step in a process. In this paper, we review methods for calculating diffusion coefficients from molecular simulation and predictive engineering models. The main achievements of our researc...
Citations
... 3D geo-visualizations of architectural/urbanised areas retrieved from satellite images [10] contribute to the comprehension and analysis of urban areas while combining satellite remote sensing and GIS into a unique system allows the analysis of the geographic space [11]. Finally, multimedia 3D cartographic applications create comprehensive platforms and communicate spatial related information by contributing to the perception of space [12]. ...
This study concerns digital tools and simulation methods necessary for the description, conception, perception, and analysis of spatial architectural and urban design. The purpose of the study is to categorize, analyses, and describeS the influence of digital simulation tools and methods in architectural and urban design. The study analyses techniques, applications, and research in the field of digital simulations of architectural/urban ensembles while also referring to the benefits of their use both at the level of scientific and spatial perception of architectural/urban design.
... Molecular dynamics (MD) simulations were performed using molecular models of the studied components that were taken from the literature. [69], toluene [70], methanol [71] and acetone [72]. Most of these models stem from previous works of our group. ...
Diffusion coefficients at infinite dilution are important basic data for all processes involving mass transfer. They can be obtained from studying samples in equilibrium using nuclear magnetic resonance spectroscopy with pulsed field gradients (PFG-NMR), a technique which is widely used in chemistry but is only rarely applied in engineering studies. This advantageous technique was employed here to measure the self-diffusion coefficients of diluted solutions of carbon dioxide and methane in the pure solvents water, ethanol, cyclohexane, toluene, methanol, and acetone at 298.15 K. For the systems (carbon dioxide + water) and (carbon dioxide + ethanol), measurements were also carried out at 308.15 K, 318.15 K and 333.15 K. Except for (methane + water) and (methane + toluene), no literature data for the methane-containing systems were previously available. At the studied solute concentrations, there is practically no difference between the self-diffusion coefficient and the mutual diffusion coefficient. The experimental results are compared to experimental literature data as well as to results from semi-empirical methods for the prediction of diffusion coefficients at infinite dilution. Furthermore, molecular dynamics simulations were carried out for all systems to determine the diffusion coefficient at infinite dilution based on force fields that were taken from the literature, and the results are compared to the experimental data and those from the classical prediction methods.
... Molecular dynamics (MD) simulations were performed using molecular models of the studied components that were taken from the literature. [69], toluene [70], methanol [71] and acetone [72]. Most of these models stem from previous works of our group. ...
Diffusion coefficients at infinite dilution are important basic data for all processes involving mass transfer. They can be obtained from studying samplesin equilibrium using nuclear magnetic resonance spectroscopy with pulsed field gradients (PFG-NMR), a technique which is widely used in chemistry but isonly rarely applied in engineering studies. This advantageous technique was employed here to measure the self-diffusion coefficients of diluted solutions ofcarbon dioxide and methane in the pure solvents water, ethanol, cyclohexane, toluene, methanol, and acetone at 298.15 K. For the systems (carbon dioxide +water) and (carbon dioxide + ethanol), measurements were also carried out at 308.15 K, 318.15 K and 333.15 K. Except for (methane + water) and (methane +toluene), no literature data for the methane-containing systems were previously available. At the studied solute concentrations, there is practically no differencebetween the self-diffusion coefficient and the mutual diffusion coefficient. The experimental results are compared to experimental literature data as well as toresults from semi-empirical methods for the prediction of diffusion coefficients at infinite dilution. Furthermore, molecular dynamics simulations were carried outfor all systems to determine the diffusion coefficient at infinite dilution based on force fields that were taken from the literature, and the results are compared tothe experimental data and those from the classical prediction methods.
... [22,23] However, since their experimental detection and analysis can still be challenging and expensive, computational tools may be valuable for this kind of investigation. [24][25][26] We were able to calculate the activity coefficients of methanol in its binary mixtures with a set of small alcohols, which allowed some insight into how the chain length and branching modify the hydrogen bond network and consequently affect their behavior. [27] Since it is fundamental to study the hydrogen bond network in binary organic solvents, it is interesting to investigate the behavior of HFIP with both an hydrogen bond acceptor (acetone) and a compound able to work both as hydrogen bond acceptor and donor (methanol). ...
Binary mixtures of hexafluoroisopropanol with either methanol or acetone are analyzed via classical molecular dynamics simulations and quantum cluster equilibrium calculations. In particular, their populations and thermodynamic properties are investigated with the binary quantum cluster equilibrium method, using our in‐house code peacemaker 2.8, upgraded with temperature‐dependent parameters. A novel approach, where the final density from classical molecular dynamics, has been used to generate the necessary reference isobars. The hydrogen bond network in both type of mixtures at molar fraction of hexafluoroisopropanol of 0.2, 0.5, and 0.8 respectively is investigated via the molecular dynamics trajectories and the cluster results. In particular, the populations show that mixed clusters are preferred in both systems even at 0.2 molar fractions of hexafluoroisopropanol. Enthalpies and entropies of vaporization are calculated for the neat and mixed systems and found to be in good agreement with experimental values.
... interactions between molecules. In the present work, the repulsive and dispersive intermolecular interactions of methanol are described by a Lennard-Jones type potential[44] and the bulk viscosity is determined on the basis of the Green-Kubo formalism[45,46]. The latter requires the evaluation of an improper time ...
A measurement procedure using a modified two-chamber pulse-echo experimental setup is presented, enabling acoustic absorption and bulk viscosity (volume viscosity) measurements in liquids up to high temperature and pressure. Acoustic absorption measurements are particularly challenging, since other dissipative effects, such as diffraction at the acoustic source and at acoustic reflectors, are typically superimposed to the measurement effect. Acoustic field simulations are performed, allowing to investigate acoustic wave propagation qualitatively. The absorption coefficient is determined by evaluating the signal spectrum’s raw moments and applying a method to identify and correct systematic measurement deviations. Measurement uncertainties are estimated by a Monte Carlo method. In order to validate the present measurement procedure, the acoustic absorption in liquid methanol, n-hexane, n-octane, and n-decane is determined experimentally and compared to literature data. The measurement results for methanol are additionally validated by comparison to bulk viscosity data sampled with molecular dynamics simulation.
... These molecular models account for the intermolecular interactions, including hydrogen bonding, by a set of Lennard-Jones sites and superimposed point charges which may or may not coincide with respect to their site position. The molecular models for the alcohols were developed by our group based on quantum chemical calculations, parameter optimization to experimental VLE data and, in the case of propan-2-ol, also to experimental data on the self-diffusion coefficient5,[47][48][49] . For water, the TIP4P/2005 force field by Abascal and Vega 47 ...
... each model which can be achieved. Furthermore, it is known that using such models, extrapolations to other thermophysical properties and other conditions than those that were used in the parametrisation are often successful [19][20][21][22]. The models can also be applied for studying fluid mixtures using wellestablished combination rules [23]. ...
... The molecular models were parametrised in a consistent way with respect to vapour-liquid equilibrium data, which is therefore described very well. Other pure component properties, such as homogeneous pvT data, caloric properties, speed of sound, interfacial properties, predicted from these models were found to be in good agreement with experimental data -where available [21,[24][25][26][27][28][29]. The MolMod database currently consists of molecular models of approximately 150 pure substances of mainly moderately sized molecules that are modelled as rigid bodies. ...
The MolMod database is presented, which is openly accessible at http://molmod.boltzmann-zuse.de andcontains intermolecular force fields for over 150 pure fluids at present. It was developed and is maintainedby the Boltzmann-Zuse Society for Computational Molecular Engineering (BZS). The set of molecularmodels in the MolMod database provides a coherent framework for molecular simulations of fluids.The molecular models in the MolMod database consist of Lennard-Jones interaction sites, pointcharges, and point dipoles and quadrupoles, which can be equivalently represented by multiple pointcharges. The force fields can be exported as input files for the simulation programmes ms2 and ls1mardyn, GROMACS, and LAMMPS. To characterise the semantics associated with the numericaldatabase content, a force field nomenclature is introduced that can also be used in other contexts inmaterials modelling at the atomistic and mesoscopic levels. The models of the pure substances thatare included in the database were generally optimised such as to yield good representations ofexperimental data of the vapour–liquid equilibrium with a focus on the vapour pressure and thesaturated liquid density. In many cases, the models also yield good predictions of caloric, transport,and interfacial properties of the pure fluids. For all models, references to the original works in whichthey were developed are provided. The models can be used straightforwardly for predictions ofproperties of fluid mixtures using established combination rules. Input errors are a major source oferrors in simulations. The MolMod database contributes to reducing such errors
... Even the amount of experimental data concerning the properties of this system is much less comprehensive. A set of models for liquid methanol, designed for application within the computer simulation methods, is quite ample [33,34,47,[50][51][52][53][54]. As concerns computer simulation studies of solutions of simple salts in methanol, we are aware of the following reports [55][56][57][58][59]. ...
... The CH 3 group is treated as a single site denominated as C. The oxygen and hydroxyl hydrogen sites are denoted as O and H, respectively. More specifically, the methanol model from [52], the model developed in the laboratory of Vrabec [53], the recently developed model from the laboratory of Vega [33], and the model from the TraPPE database [54] are used. They are denominated as L1, L2, OPLS/2016, according to table 1 of [33], and as TraPPE, respectively. ...
... In addition, we complement the L2 methanol model [53] with the model for NaCl originally proposed in the work from the same laboratory [63] and later adjusted and applied to describe the properties of aqueous and methanolic NaCl solutions in [57,64]. Again, the LB combination rules are used for this model. ...
Isothermal-isobaric molecular dynamics simulations are used to examine the microscopic structure and principal thermodynamic properties of a model solution consisting of NaCl salt dissolved in methanol solvent. Four united atom force fields for methanol are involved. Concerning ion solutes we used the Joung-Cheatham, Smith-Dang models as well as the model from the laboratory of Vrabec. Our principal focus is to evaluate the quality of predictions of different combinations of models for basic properties of these solutions. Specifically, we explored the change of density on molality, the structural properties in terms of various pair distribution functions, the coordination numbers, the number of ion pairs and the average number of hydrogen bonds. In addition, changes of the self-diffusion coefficients of species, the solvent dielectric constant and the evolution of the surface tension with ion concentration are described.
... All the simulations were carried out with the LAMMPS package [44]. The confined system consists in a fluid -TIP4P/2005 water [45] or methanol (MeOH) [46,47] -between two parallel walls -graphene, or a generic hydrophobic wall made of Lennard-Jones (LJ) particles -with periodic boundary conditions applied in the directions parallel to the walls ( Fig. 1), see details in SI Appendix. The surfaces were characterized by contact angles of θ ∼ 134 • for water-LJ walls, θ ∼ 80 • for watergraphene, θ ∼ 100 • for MeOH-LJ walls and θ ∼ 0 • for MeOH-graphene. ...
Cooling down water in its supercooled regime has been widely considered to better understand the bulk transport properties of this ubiquitous liquid. Here we apply the same approach to investigate the wall slip induced by low interfacial friction, a key factor in the performance of nanofluidic systems. Specifically, we investigated the temperature dependence of friction and slip for water and methanol on model Lennard-Jones walls and on graphene. Surprisingly, although interfacial friction and viscosity in bulk follow the same fundamental laws and are proportional at high temperatures, the relation of proportionality breaks down in the supercooled regime. This implies that wall slip, controlled by the ratio between viscosity and friction, increases in the deep supercooled regime -- by up to a factor of 5 for water on graphene. Whereas most previous studies have focused on the role of static features of the interface, here we focus on the intriguing role of dynamics. We find that the interfacial density relaxation of the fluid -- and how it evolves with respect to the bulk one -- governs the temperature dependence of wall slip. Overall, exploring the temperature dependence of water-wall slip provides new insight on its molecular mechanisms, and can also shed light on the bulk transport properties of water.
... Even the amount of experimental data concerning the properties of this system is much less comprehensive. A set of models for liquid methanol, designed for application within the computer simulation methods, is quite ample [33,34,47,[50][51][52][53][54]. As concerns computer simulation studies of solutions of simple salts in methanol, we are aware of the following reports [55][56][57][58][59]. ...
... The CH 3 group is treated as a single site denominated as C. The oxygen and hydroxyl hydrogen sites are denoted as O and H, respectively. More specifically, the methanol model from [52], the model developed in the laboratory of Vrabec [53], the recently developed model from the laboratory of Vega [33], and the model from the TraPPE database [54] are used. They are denominated as L1, L2, OPLS/2016, according to table 1 of [33], and as TraPPE, respectively. ...
... In addition, we complement the L2 methanol model [53] with the model for NaCl originally proposed in the work from the same laboratory [63] and later adjusted and applied to describe the properties of aqueous and methanolic NaCl solutions in [57,64]. Again, the LB combination rules are used for this model. ...
