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Agrawal NR, Wang R. Self-Consistent Description of Vapor-Liquid Interface in Ionic Fluids. PHYSICAL REVIEW LETTERS 2022; 129:228001. [PMID: 36493445 DOI: 10.1103/physrevlett.129.228001] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 11/03/2022] [Indexed: 06/17/2023]
Abstract
Inhomogeneity of ion correlation widely exists in many physicochemical, soft matter, and biological systems. Here, we apply the modified Gaussian renormalized fluctuation theory to study the classic example of the vapor-liquid interface of ionic fluids. The ion correlation is decomposed into a short-range contribution associated with the local electrostatic environment and a long-range contribution accounting for the spatially varying ionic strength and dielectric permittivity. For symmetric salt, both the coexistence curve and the interfacial tension predicted by our theory are in quantitative agreement with simulation data reported in the literature. Furthermore, we provide the first theoretical prediction of interfacial structure for asymmetric salt, highlighting the importance of capturing local charge separation.
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Affiliation(s)
- Nikhil R Agrawal
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
| | - Rui Wang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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2
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Hatch HW, Hall SW, Errington JR, Shen VK. Improving the efficiency of Monte Carlo simulations of ions using expanded grand canonical ensembles. J Chem Phys 2019; 151:144109. [PMID: 31615250 PMCID: PMC7254863 DOI: 10.1063/1.5123683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
While ionic liquids have promising applications as industrial solvents, predicting their fluid phase properties and coexistence remains a challenge. Grand canonical Monte Carlo simulation is an effective method for such predictions, but equilibration is hampered by the apparent requirement to insert and delete neutral sets of ions simultaneously in order to maintain charge neutrality. For relatively high densities and low temperatures, previously developed methods have been shown to be essential in improving equilibration by gradual insertion and deletion of these neutral sets of ions. We introduce an expanded ensemble approach which may be used in conjunction with these existing methods to further improve efficiency. Individual ions are inserted or deleted in one Monte Carlo trial rather than simultaneous insertion/deletion of neutral sets. We show how charge neutrality is maintained and show rigorous quantitative agreement between the conventional and the proposed expanded ensemble approaches, but with up to an order of magnitude increase in efficiency at high densities. The expanded ensemble approach is also more straightforward to implement than simultaneous insertion/deletion of neutral sets, and its implementation is demonstrated within open source software.
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Affiliation(s)
- Harold W. Hatch
- Chemical Informatics Research Group, Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8380, USA
| | - Steven W. Hall
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA
| | - Jeffrey R. Errington
- Department of Chemical and Biological Engineering, University at Buffalo, Buffalo, NY 14260, USA
| | - Vincent K. Shen
- Chemical Informatics Research Group, Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8380, USA
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3
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Bartsch H, Bier M, Dietrich S. Smectic phases in ionic liquid crystals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:464002. [PMID: 28972199 DOI: 10.1088/1361-648x/aa9090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which carry charges and therefore combine properties of liquid crystals, e.g. the formation of mesophases, and of ionic liquids, such as low melting temperatures and tiny triple-point pressures. Previous density functional calculations have revealed that the phase behavior of ILCs is strongly affected by their molecular properties, i.e. their aspect ratio, the loci of the charges, and their interaction strengths. Here, we report new findings concerning the phase behavior of ILCs as obtained by density functional theory and Monte Carlo simulations. The most important result is the occurrence of a novel, wide smectic-A phase [Formula: see text], at low temperature, the layer spacing of which is larger than that of the ordinary high-temperature smectic-A phase [Formula: see text]. Unlike the ordinary smectic S A phase, the structure of the [Formula: see text] phase consists of alternating layers of particles oriented parallel to the layer normal and oriented perpendicular to it.
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Affiliation(s)
- Hendrik Bartsch
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, 70569 Stuttgart, Germany. Institut für Theoretische Physik IV, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
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4
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Butlitsky MA, Zelener BB, Zelener BV. Critical point of gas-liquid type phase transition and phase equilibrium functions in developed two-component plasma model. J Chem Phys 2014; 141:024511. [PMID: 25028031 DOI: 10.1063/1.4886403] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A two-component plasma model, which we called a "shelf Coulomb" model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The "shelf Coulomb" model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ɛ parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ɛ and γ = βe(2)n(1/3) (where β = 1/kBT, n is the particle's density, kB is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ɛ and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ɛ(crit) ≈ 13(T(*)(crit) ≈ 0.076), γ(crit) ≈ 1.8(v(*)(crit) ≈ 0.17), P(*)(crit) ≈ 0.39, where specific volume v* = 1/γ(3) and reduced temperature T(*) = ɛ(-1).
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Affiliation(s)
- M A Butlitsky
- Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2
| | - B B Zelener
- Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2
| | - B V Zelener
- Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2
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5
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Lamperski S, Waśko M, Henderson D. Solidification of the charged hard-sphere fluid. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2013.773432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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6
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SABIR AK, BHUIYAN LB, OUTHWAITE CW. Influence of ion size and valence on classical ionic criticality. Mol Phys 2010. [DOI: 10.1080/002689798169087] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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7
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Martín-Betancourt M, Romero-Enrique JM, Rull LF. Liquid−Vapor Coexistence in a Primitive Model for a Room-Temperature Ionic Liquid. J Phys Chem B 2009; 113:9046-9. [DOI: 10.1021/jp903709k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marianela Martín-Betancourt
- Departamento de Física Atómica, Molecular y Nuclear, Area de Física Teórica, Universidad de Sevilla, Apartado de Correos 1065, 41080 Sevilla, Spain
| | - José M. Romero-Enrique
- Departamento de Física Atómica, Molecular y Nuclear, Area de Física Teórica, Universidad de Sevilla, Apartado de Correos 1065, 41080 Sevilla, Spain
| | - Luis F. Rull
- Departamento de Física Atómica, Molecular y Nuclear, Area de Física Teórica, Universidad de Sevilla, Apartado de Correos 1065, 41080 Sevilla, Spain
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8
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Hynninen AP, Panagiotopoulos AZ. Simulations of phase transitions and free energies for ionic systems. Mol Phys 2008. [DOI: 10.1080/00268970802112160] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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9
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10
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Pauschenwein GJ, Caillol JM, Levesque D, Weis JJ, Schöll-Paschinger E, Kahl G. Liquid-vapor transition of systems with mean field universality class. J Chem Phys 2007; 126:014501. [PMID: 17212494 DOI: 10.1063/1.2405353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We have considered a system where the interaction, v(r)=v(IS)(r)+xi(2)v(MF)(r), is given as a linear combination of two potentials, each of which being characterized with a well-defined critical behavior: for v(IS)(r) we have chosen the potential of the restricted primitive model which is known to belong to the three-dimensional Ising universality class, while for v(MF)(r) we have considered a long-range interaction in the Kac [J. Math. Phys. 4, 216 (1963)] limit, displaying mean field (MF) behavior. We study the performance of two theoretical approaches and of computer simulations in the critical region for this particular system and give a detailed comparison between theories and simulation of the critical region and the location of the critical point. Having shown by theoretical arguments that the system belongs to the MF universality class for any positive value of xi and shows nonclassical behavior only for xi=0, we examine to which extent theoretical approximations and simulation can reproduce this behavior. While in this limiting case theoretical approaches are known to fail, we find good agreement for the critical properties between the theoretical approaches and the simulations for xi(2) larger than 0.05.
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Affiliation(s)
- Gernot J Pauschenwein
- CMS and Institut für Theoretische Physik, TU Wien, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria.
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11
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Zoetekouw B, van Roij R. Volume terms for charged colloids: a grand-canonical treatment. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:021403. [PMID: 16605335 DOI: 10.1103/physreve.73.021403] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Indexed: 05/08/2023]
Abstract
We present a study of thermodynamic properties of suspensions of charged colloids on the basis of linear Poisson-Boltzmann theory. We calculate the effective Hamiltonian of the colloids by integrating out the ionic degrees of freedom grand canonically. This procedure not only yields the well-known pairwise screened-Coulomb interaction between the colloids, but also additional volume terms that affect the phase behavior and the thermodynamic properties, such as the osmotic pressure. These calculations are greatly facilitated by the grand-canonical character of our treatment of the ions and allow for relatively fast computations compared to earlier studies in the canonical ensemble. Moreover, the present derivation of the volume terms are relatively simple, make a direct connection with Donnan equilibrium, yield an explicit expression for the effective screening constant, and allow for extensions to include, for instance, nonlinear effects.
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Affiliation(s)
- Bas Zoetekouw
- Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584CE Utrecht, The Netherlands
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12
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Aqua JN, Banerjee S, Fisher ME. Criticality in charge-asymmetric hard-sphere ionic fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:041501. [PMID: 16383379 DOI: 10.1103/physreve.72.041501] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Indexed: 05/05/2023]
Abstract
Phase separation and criticality are analyzed in z:1 charge-asymmetric ionic fluids of equisized hard spheres by generalizing the Debye-Hückel approach combined with ionic association, cluster solvation by charged ions, and hard-core interactions, following lines developed by Fisher and Levin for the 1:1 case (i.e., the restricted primitive model). Explicit analytical calculations for 2:1 and 3:1 systems account for ionic association into dimers, trimers, and tetramers and subsequent multipolar cluster solvation. The reduced critical temperatures, Tc* (normalized by z), decrease with charge asymmetry, while the critical densities increase rapidly with . The results compare favorably with simulations and represent a distinct improvement over all current theories such as the mean spherical approximation, symmetric Poisson-Boltzmann theory, etc. For z not equal to 1, the interphase Galvani (or absolute electrostatic) potential difference, Deltaphi(T), between coexisting liquid and vapor phases is calculated and found to vanish as absolute value (T-Tc) beta when T-->Tc-with, since our approximations are classical, beta = (1/2). Above Tc, the compressibility maxima and so-called k-inflection loci (which aid the fast and accurate determination of the critical parameters) are found to exhibit a strong z dependence.
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Affiliation(s)
- Jean-Noël Aqua
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 USA
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13
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Kalyuzhnyi YV, Kahl G, Cummings PT. Phase coexistence in a polydisperse charged hard-sphere fluid: Polymer mean spherical approximation. J Chem Phys 2005; 123:124501. [PMID: 16392492 DOI: 10.1063/1.2042347] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We have reconsidered the phase behavior of a polydisperse mixture of charged hard spheres (CHSs) introducing the concept of minimal size neutral clusters. We thus take into account ionic association effects observed in charged systems close to the phase boundary where the properties of the system are dominated by the presence of neutral clusters while the amount of free ions or charged clusters is negligible. With this concept we clearly pass beyond the simple level of the mean spherical approximation (MSA) that we have presented in our recent study of a polydisperse mixture of CHS [Yu. V. Kalyuzhnyi, G. Kahl, and P. T. Cummings, J. Chem. Phys. 120, 10133 (2004)]. Restricting ourselves to a 1:1 and possibly size-asymmetric model we treat the resulting polydisperse mixture of neutral, polar dimers within the framework of the polymer MSA, i.e., a concept that--similar as the MSA--readily can be generalized from the case of a mixture with a finite number of components to the polydisperse case: again, the model belongs to the class of truncatable free-energy models so that we can map the formally infinitely many coexistence equations onto a finite set of coupled, nonlinear equations in the generalized moments of the distribution function that characterizes the system. This allows us to determine the full phase diagram (in terms of binodals as well as cloud and shadow curves), we can study fractionation effects on the level of the distribution functions of the coexisting daughter phases, and we propose estimates on how the location of the critical point might vary in a polydisperse mixture with an increasing size asymmetry and polydispersity.
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Affiliation(s)
- Yurij V Kalyuzhnyi
- Institute for Condensed Matter Physics, Svientsitskoho 1, 79011 Lviv, Ukraine.
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14
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15
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Pizio O, Sokołowski S. Phase behavior of the restricted primitive model of ionic fluids with association in slitlike pores. Density-functional approach. J Chem Phys 2005; 122:144707. [PMID: 15847553 DOI: 10.1063/1.1883165] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present results of investigations of condensation of restricted primitive model of electrolyte solutions with association between oppositely charged ions confined to slitlike pores. The associative interaction leads to the formation of ionic pairs. It is accounted for by incorporating the first-order thermodynamic perturbation theory into the free energy functional. In order to elucidate the role of association, the phase diagrams are compared with those obtained by us recently [O. Pizio et al., J. Chem. Phys. 121, 11957 (2004)] for the restricted primitive model. The inclusion of the association into the theory leads to lowering the critical temperature for the fluid confined to pores with uncharged and with charged walls. We have observed that the average fraction of bonded ions is high along the coexistence envelope.
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Affiliation(s)
- O Pizio
- Instituto de Química de la UNAM, Coyoacán 04510, D.F., Mexico.
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16
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Delville A. Influence of Confinement on the Electrostatic Interaction between Charged Colloids: a (N,V,T) Monte Carlo Study within Hyperspherical Geometry. J Phys Chem B 2005; 109:8164-70. [PMID: 16851954 DOI: 10.1021/jp044711l] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Monte Carlo simulations within closed hyperspherical geometry are used to analyze the ionic distribution around two confined charged colloids to determine the origin of the net attraction recently reported in the literature. A scaling procedure is used to compare our numerical results obtained with small ideal colloids with the conclusion of the measurements performed with large silica colloids. Although no electrostatic attraction is detected under confinement, our simulations exhibit a significant reduction of the electrostatic repulsion between charged colloids confined between two weakly charged walls. After rescaling to reproduce the electrostatic repulsion between large confined colloids, our numerical results are qualitatively consistent with the reported attraction because we reasonably expect a reduction of the electrostatic force between such confined colloids below the order of magnitude of their van der Waals attraction.
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Affiliation(s)
- A Delville
- CRMD, CNRS, 1B rue de la Férollerie, 45071 Orléans Cedex 02, France
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17
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Caballero JB, Puertas AM, Fernández-Barbero A, de las Nieves FJ. Oppositely charged colloidal binary mixtures: A colloidal analog of the restricted primitive model. J Chem Phys 2004; 121:2428-35. [PMID: 15260798 DOI: 10.1063/1.1767995] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The equilibrium phase diagram of a colloidal system composed of 1:1 mixture of positive and negative particles with equal charge is studied by means of Monte Carlo simulations. The system is the colloidal analog of the restricted primitive model (RPM) for ionic fluids. A liquid-gas transition is found in the low-temperature-low-density region, similar to the liquid-gas transition in the RPM. The fluid-crystal transition is also studied, and the liquid phase is shown to be stable in a narrow range of temperatures. In the liquid, the pair distribution function shows alternating layers of particles with opposite sign of charge surrounding every particle. In the vapor phase, clusters of particles are observed, again in agreement with the RPM. However, a decreasing distribution of clusters is obtained, instead of the discrimination between charged and neutral clusters found in the RPM.
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Affiliation(s)
- José B Caballero
- Group of Complex Fluids Physics, Department of Applied Physics, University of Almeria, 04120, Spain
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18
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Kalyuzhnyi YV, Kahl G, Cummings PT. Phase coexistence in polydisperse charged hard-sphere fluids: Mean spherical approximation. J Chem Phys 2004; 120:10133-45. [PMID: 15268036 DOI: 10.1063/1.1737291] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Taking advantage of the availability of the analytic solution of the mean spherical approximation for a mixture of charged hard spheres with an arbitrary number of components we show that the polydisperse fluid mixture of charged hard spheres belongs to the class of truncatable free energy models, i.e., to those systems where the thermodynamic properties can be represented by a finite number of (generalized) moments of the distribution function that characterizes the mixture. Thus, the formally infinitely many equations that determine the parameters of the two coexisting phases can be mapped onto a system of coupled nonlinear equations in these moments. We present the formalism and demonstrate the power of this approach for two systems; we calculate the full phase diagram in terms of cloud and shadow curves as well as binodals and discuss the distribution functions of the coexisting daughter phases and their charge distributions.
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Affiliation(s)
- Yurij V Kalyuzhnyi
- Institute for Condensed Matter Physics, Svientsitskoho 1, 79011 Lviv, Ukraine
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19
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Kim YC, Fisher ME. Fluid Critical Points from Simulations: The Bruce−Wilding Method and Yang−Yang Anomalies. J Phys Chem B 2004. [DOI: 10.1021/jp037071f] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Young C. Kim
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742
| | - Michael E. Fisher
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742
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20
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Cheong DW, Panagiotopoulos AZ. Critical parameters of unrestricted primitive model electrolytes with charge asymmetries up to 10:1. J Chem Phys 2003. [DOI: 10.1063/1.1612473] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Daub CD, Patey GN, Camp PJ. Liquid–vapor criticality in a fluid of charged hard dumbbells. J Chem Phys 2003. [DOI: 10.1063/1.1609192] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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KRISTÓF TAMÁS, BODA DEZSŐ, LISZI JÁNOS, HENDERSON DOUGLAS, CARLSON ERIC. Vapour-liquid equilibrium of the charged Yukawa fluid from Gibbs ensemble Monte Carlo simulations and the mean spherical approximation. Mol Phys 2003. [DOI: 10.1080/0026897031000068523] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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23
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24
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Daub CD, Camp PJ, Patey GN. The constant-volume heat capacity of near-critical fluids with long-range interactions: A discussion of different Monte Carlo estimates. J Chem Phys 2003. [DOI: 10.1063/1.1540630] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Kulinskii VL, Malomuzh NP. Dipole fluid as a basic model for the equation of state of ionic liquids in the vicinity of their critical point. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 67:011501. [PMID: 12636500 DOI: 10.1103/physreve.67.011501] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2002] [Revised: 08/15/2002] [Indexed: 05/24/2023]
Abstract
A model of dipole fluid for ionic liquids similar to molten NaCl is proposed. The estimates for the critical parameters are obtained with the help of the van der Waals equation of state. The influence of the rotation on the characteristics of a dipole pair and the location of the critical point is discussed. The dissociation of such a fluid near the critical point is considered.
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Affiliation(s)
- V L Kulinskii
- Department of Theoretical Physics, Odessa National University, 2 Dvoryanskaya, 270100 Odessa, Ukraine.
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26
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Romero-Enrique JM, Rull LF, Panagiotopoulos AZ. Dipolar origin of the gas-liquid coexistence of the hard-core 1:1 electrolyte model. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 66:041204. [PMID: 12443188 DOI: 10.1103/physreve.66.041204] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2002] [Indexed: 05/24/2023]
Abstract
We present a systematic study of the effect of the ion pairing on the gas-liquid phase transition of hard-core 1:1 electrolyte models. We study a class of dipolar dimer models that depend on a parameter R(c), the maximum separation between the ions that compose the dimer. This parameter can vary from sigma(+/-) that corresponds to the tightly tethered dipolar dimer model to R(c)--> infinity that corresponds to the Stillinger-Lovett description of the free ion system. The coexistence curve and critical point parameters are obtained as a function of R(c) by grand-canonical Monte Carlo techniques. Our results show that this dependence is smooth but nonmonotonic and converges asymptotically towards the free ion case for relatively small values of R(c). This fact allows us to describe the gas-liquid transition in the free ion model as a transition between two dimerized fluid phases. The role of the unpaired ions can be considered as a perturbation of this picture.
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Affiliation(s)
- J M Romero-Enrique
- Departamento de Física Atómica, Molecular y Nuclear, Area de Física Teórica, Universidad de Sevilla, Apartado Correos 1065, 41080 Seville, Spain.
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27
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Caillol JM, Levesque D, Weis JJ. Critical behavior of the restricted primitive model revisited. J Chem Phys 2002. [DOI: 10.1063/1.1480009] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Kulinskii VL, Malomuzh NP. Critical behavior of ionic liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 65:061506. [PMID: 12188731 DOI: 10.1103/physreve.65.061506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2001] [Revised: 04/05/2002] [Indexed: 05/23/2023]
Abstract
The renormalization of the Landau-Ginzburg Hamiltonian for a system with Coulombic interactions caused by spatially inhomogeneous polarizational effects is discussed. It is shown that for ionic liquids with a strong dependence of the degree of dissociation on density, the nonclassical fluctuation region is significantly narrowed. The essential role of the association of ions is noted.
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Affiliation(s)
- V L Kulinskii
- Department of Theoretical Physics, Odessa National University, 2 Dvoryanskaya Strasse, 270100 Odessa, Ukraine
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29
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Luijten E, Fisher ME, Panagiotopoulos AZ. Universality class of criticality in the restricted primitive model electrolyte. PHYSICAL REVIEW LETTERS 2002; 88:185701. [PMID: 12005698 DOI: 10.1103/physrevlett.88.185701] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2001] [Indexed: 05/23/2023]
Abstract
The 1:1 equisized hard-sphere electrolyte or restricted primitive model has been simulated via grand-canonical fine-discretization Monte Carlo. Newly devised unbiased finite-size extrapolation methods using loci in the temperature-density or (T,rho) plane of isothermal rho(2-k) vs pressure inflections, of Q identical with<m(2)>(2)/<m(4)> maxima, and of canonical and C(V) criticality, yield estimates of (T(c),rho(c)) to +/-(0.04,3)%. Extrapolated exponents and Q ratio are (gamma,nu,Q(c)) = [1.24(3), 0.63(3); 0.624(2)], which support Ising (n = 1) behavior with (1.23(9), 0.630(3); 0.623(6)), but exclude classical, XY (n = 2), self-avoiding walk (n = 0), and n = 1 criticality with potentials varphi(r)>Phi/r(4.9) when r-->infinity.
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Affiliation(s)
- Erik Luijten
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
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Yan Q, de Pablo JJ. Phase equilibria of charge-, size-, and shape-asymmetric model electrolytes. PHYSICAL REVIEW LETTERS 2002; 88:095504. [PMID: 11864025 DOI: 10.1103/physrevlett.88.095504] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2001] [Indexed: 05/23/2023]
Abstract
The low-temperature phase behavior of two 2:1 hard-core electrolyte models has been investigated by Monte Carlo simulations. In the first model, both bivalent cations and monovalent anions are spherical, and the charges are located at the ion's centers; in the second model, bivalent cations are modeled as rigid dimers composed of two tangent hard spheres, each carrying a positive charge at the center. It is found that the critical temperature and the critical density are strongly affected by the size asymmetry and the shape of the ions. The results presented in this work provide insights into the behavior of charged colloidal suspensions and polyelectrolytes, where large, symmetric or asymmetric ionic species carrying like charges can attract each other and give rise to thermodynamically unstable conditions.
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Affiliation(s)
- Qiliang Yan
- Department of Chemical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
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31
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Yan Q, de Pablo JJ. Effects of charge, size, and shape-asymmetry on the phase behavior of model electrolytes. J Chem Phys 2002. [DOI: 10.1063/1.1435567] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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33
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Guissani Y, Guillot B. Chemical reactivity and phase behavior of NH4Cl by molecular dynamics simulations. II. The liquid–vapor coexistence curve. J Chem Phys 2002. [DOI: 10.1063/1.1431592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Panagiotopoulos AZ, Fisher ME. Phase transitions in 2:1 and 3:1 hard-core model electrolytes. PHYSICAL REVIEW LETTERS 2002; 88:045701. [PMID: 11801139 DOI: 10.1103/physrevlett.88.045701] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2001] [Indexed: 05/23/2023]
Abstract
Critical temperatures, T(c), densities, rho(c), and coexistence curves for 2:1 and 3:1 hard-core model electrolytes have been found by fine-discretization Monte Carlo simulation. The size ratio of + and - ions strongly affects T(c) and rho(c); the trends contradict most current theories. Large multivalent ions screened by small monovalent counterions exhibit normal gas-liquid transitions of direct relevance to phase separation in charge-stabilized colloids. Conversely, extrapolation suggests the absence of such transitions for sufficiently small multivalent ions with large monovalent counterions.
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Oleinikova A, Bonetti M. Electrical conductivity of highly concentrated electrolytes near the critical consolute point: A study of tetra-n-butylammonium picrate in alcohols of moderate dielectric constant. J Chem Phys 2001. [DOI: 10.1063/1.1415458] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Almarza NG, Enciso E. Critical behavior of ionic solids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 64:042501. [PMID: 11690066 DOI: 10.1103/physreve.64.042501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2001] [Indexed: 05/23/2023]
Abstract
Phase transitions of lattice models of ionic crystals are studied by computer simulation. The nature of order-disorder transitions on different crystal structures is established and compared with the behavior of related Ising models. It is found that for both, continuous and first order transitions the basic features seem to be similar to those of Ising systems.
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Affiliation(s)
- N G Almarza
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense, E-28040 Madrid, Spain
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37
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Schröer W. Generalization of the Kirkwood - Fröhlich theory of dielectric polarization for ionic fluids. J Mol Liq 2001. [DOI: 10.1016/s0167-7322(01)00178-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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38
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Flores-Mena JE, Barbosa MC, Levin Y. Criticality in confined ionic fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 63:066104. [PMID: 11415170 DOI: 10.1103/physreve.63.066104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2001] [Indexed: 05/23/2023]
Abstract
A theory of a confined two-dimensional electrolyte is presented. The positive and negative ions, interacting by a 1/r potential, are constrained to move on an interface separating two solvents with dielectric constants epsilon(1) and epsilon(2). It is shown that the Debye-Hückel type of theory predicts that this two-dimensional Coulomb fluid should undergo a phase separation into a coexisting liquid (high-density) and gas (low-density) phases. We argue, however, that the formation of polymerlike chains of alternating positive and negative ions can prevent this phase transition from taking place.
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Affiliation(s)
- J E Flores-Mena
- Facultad de Ciencias de la Electrónica, Universidad Autónoma de Puebla, AP J-48, Puebla 72570, Puebla, Mexico
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Orkoulas G, Fisher ME, Panagiotopoulos AZ. Precise simulation of criticality in asymmetric fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 63:051507. [PMID: 11414909 DOI: 10.1103/physreve.63.051507] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2000] [Indexed: 05/23/2023]
Abstract
Extensive grand canonical Monte Carlo simulations have been performed for the hard-core square-well fluid with interaction range b=1.5 sigma. The critical exponent for the correlation length has been estimated in an unbiased fashion as nu=0.63+/-0.03 via finite-size extrapolations of the extrema of properties measured along specially constructed, asymptotically critical loci that represent pseudosymmetry axes. The subsequent location of the critical point achieves a precision of five parts in 10(4) for Tc and about 0.3% for the critical density rhoc. The effective exponents gamma+(eff) and beta(eff) indicate Ising-type critical-point values to within 2% and 5.6%, respectively, convincingly distinguishing the universality class from the "nearby" XY and n=0 (self-avoiding walk) classes. Simulations of the heat capacity CV(T,rho) and d2psigma/dT2, where psigma is the vapor pressure below Tc, suggest a negative but small Yang-Yang anomaly, i.e., a specific-heat-like divergence in the corresponding chemical potential derivative (d2 musigma/dT2) that requires a revision of the standard asymptotic scaling description of asymmetric fluids.
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Affiliation(s)
- G Orkoulas
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2431, USA
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Yan Q, de Pablo JJ. Phase equilibria of size-asymmetric primitive model electrolytes. PHYSICAL REVIEW LETTERS 2001; 86:2054-2057. [PMID: 11289853 DOI: 10.1103/physrevlett.86.2054] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2000] [Indexed: 05/23/2023]
Abstract
The low-temperature phase coexistence of size-asymmetric primitive model electrolyte solutions has been investigated by means of Monte Carlo simulations. Binodal curves and critical parameters are reported as a function of size ratio lambda = sigma(+)/sigma(-) in the range 0.05 to 1. Both the critical temperature and the critical density are found to decrease as lambda decreases. These trends are in conflict with available theoretical predictions. For highly asymmetric systems, the depression of the critical parameters is accompanied by the formation of large chainlike and ringlike structures, thereby giving rise to considerable finite-size effects.
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Affiliation(s)
- Q Yan
- Department of Chemical Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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41
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Yan Q, de Pablo JJ. Phase equilibria and clustering in size-asymmetric primitive model electrolytes. J Chem Phys 2001. [DOI: 10.1063/1.1335653] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Bianchi HL, Japas ML. Phase equilibria of a near-critical ionic system. Critical exponent of the order parameter. J Chem Phys 2001. [DOI: 10.1063/1.1409362] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Camp PJ, Patey GN. Coexistence and criticality of fluids with long-range potentials. J Chem Phys 2001. [DOI: 10.1063/1.1329134] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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45
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Ciach A, Stell G. Why the Ising and continuous-space models of ionic systems exhibit essentially different critical behavior. J Chem Phys 2001. [DOI: 10.1063/1.1329138] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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46
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Romero-Enrique JM, Orkoulas G, Panagiotopoulos AZ, Fisher ME. Coexistence and criticality in size-asymmetric hard-core electrolytes. PHYSICAL REVIEW LETTERS 2000; 85:4558-4561. [PMID: 11082595 DOI: 10.1103/physrevlett.85.4558] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2000] [Indexed: 05/23/2023]
Abstract
Liquid-vapor coexistence curves and critical parameters for hard-core 1:1 electrolyte models with diameter ratios lambda = sigma(-)/sigma(+) = 1 to 5.7 have been studied by fine-discretization Monte Carlo methods. Normalizing via the length scale sigma(+/-) = 1 / 2(sigma(+)+sigma(-)), relevant for the low densities in question, both T(*)(c) ( = k(B)T(c)sigma(+/-)/q(2)) and rho(*)(c) ( = rho(c)sigma(3)(+/-)) decrease rapidly (from approximately 0.05 to 0.03 and 0.08 to 0.04, respectively) as lambda increases. These trends, which unequivocally contradict current theories, are closely mirrored by results for tightly tethered dipolar dimers (with T(*)(c) lower by approximately 0%-11% and rho(*)(c) greater by 37%-12%).
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Affiliation(s)
- JM Romero-Enrique
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2431, USA
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47
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Orkoulas G, Panagiotopoulos AZ, Fisher ME. Criticality and crossover in accessible regimes. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 2000; 61:5930-5939. [PMID: 11031656 DOI: 10.1103/physreve.61.5930] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/1999] [Indexed: 05/23/2023]
Abstract
The near-critical behavior of (d = 3)-dimensional Ising-model ferromagnets or simple lattice gases with equivalent first, second, and third nearest-neighbor interactions is studied through Monte Carlo simulations using histogram reweighting techniques and comparisons with series expansions. By carefully analyzing numerical data from relatively small finite systems using scaling and extrapolation methods, it is demonstrated that one can reliably estimate critical exponents, critical temperatures, and universal amplitude ratios, thereby distinguishing convincingly between different "nearby" universality classes and revealing systematic crossover effects. This study is preparatory to extending similar techniques to study criticality in continuum fluid models lacking symmetries, with Coulomb interactions, etc.
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Affiliation(s)
- G Orkoulas
- Institute for Physical Science and Technology, University of Maryland, College Park 20742-2431, USA
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16 Ionic fluids. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1874-5644(00)80006-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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50
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Yan Q, de Pablo JJ. Hyper-parallel tempering Monte Carlo: Application to the Lennard-Jones fluid and the restricted primitive model. J Chem Phys 1999. [DOI: 10.1063/1.480282] [Citation(s) in RCA: 282] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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