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Martínez-Ratón Y, Velasco E. Orientational ordering in a fluid of hard kites: A density-functional-theory study. Phys Rev E 2020; 102:052128. [PMID: 33327136 DOI: 10.1103/physreve.102.052128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/09/2020] [Indexed: 11/07/2022]
Abstract
Using density-functional theory we theoretically study the orientational properties of uniform phases of hard kites-two isosceles triangles joined by their common base. Two approximations are used: scaled particle theory and a new approach that better approximates third virial coefficients of two-dimensional hard particles. By varying some of their geometrical parameters, kites can be transformed into squares, rhombuses, triangles, and also very elongated particles, even reaching the hard-needle limit. Thus, a fluid of hard kites, depending on the particle shape, can stabilize isotropic, nematic, tetratic, and triatic phases. Different phase diagrams are calculated, including those of rhombuses, and kites with two of their equal interior angles fixed to 90^{∘}, 60^{∘}, and 75^{∘}. Kites with one of their unequal angles fixed to 72^{∘}, which have been recently studied via Monte Carlo simulations, are also considered. We find that rhombuses and kites with two equal right angles and not too large anisometry stabilize the tetratic phase but the latter stabilize it to a much higher degree. By contrast, kites with two equal interior angles fixed to 60^{∘} stabilize the triatic phase to some extent, although it is very sensitive to changes in particle geometry. Kites with the two equal interior angles fixed to 75^{∘} have a phase diagram with both tetratic and triatic phases, but we show the nonexistence of a particle shape for which both phases are stable at different densities. Finally, the success of the new theory in the description of orientational order in kites is shown by comparing with Monte Carlo simulations for the case where one of the unequal angles is fixed to 72^{∘}. These particles also present a phase diagram with stable tetratic and triatic phases.
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Affiliation(s)
- Yuri Martínez-Ratón
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matemáticas, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Avenida de la Universidad 30, E-28911, Leganés, Madrid, Spain
| | - Enrique Velasco
- Departamento de Física Teórica de la Materia Condensada, Instituto de Física de la Materia Condensada (IFIMAC) and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049, Madrid, Spain
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2
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Lopes JT, M. Franco LF. New Thermodynamic Approach for Nonspherical Molecules Based on a Perturbation Theory for Ellipsoids. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b00766] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joyce T. Lopes
- School of Chemical Engineering, University of Campinas, Av. Albert Einstein 500, 13083-852 Campinas, Brazil
| | - Luís F. M. Franco
- School of Chemical Engineering, University of Campinas, Av. Albert Einstein 500, 13083-852 Campinas, Brazil
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Nascimento ES. Nematic-isotropic transition in a density-functional theory for hard spheroidal colloids. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:136. [PMID: 30467606 DOI: 10.1140/epje/i2018-11746-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 10/26/2018] [Indexed: 06/09/2023]
Abstract
We introduce a density-functional formalism based on the Parsons-Lee and the generalized van der Waals theories in order to describe the thermodynamics of anisotropic particle systems with steric interactions. For ellipsoids of revolution, the orientational distribution function is obtained by minimizing the free energy functional and the equations of state are determined. The system exhibits a nematic-isotropic discontinuous transition, characterized by a phase separation between nematic and isotropic phases at finite as well low packing fractions. The model presents a phase behavior which is in good agreement with Monte Carlo simulations for finite aspect ratios.
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Affiliation(s)
- E S Nascimento
- Instituto de Física, Universidade de São Paulo, 05314-970, São Paulo, SP, Brazil.
- Liquid Crystal Institute, Kent State University, Kent, OH, USA.
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Palffy-Muhoray P, Virga EG, Zheng X. Onsager's missing steps retraced. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:475102. [PMID: 29039737 DOI: 10.1088/1361-648x/aa942b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Onsager's paper on phase transition and phase coexistence in anisotropic colloidal systems is a landmark in the theory of lyotropic liquid crystals. However, an uncompromising scrutiny of Onsager's original derivation reveals that it would be rigorously valid only for ludicrous values of the system's number density (of the order of the reciprocal of the number of particles). Based on Penrose's tree identity and an appropriate variant of the mean-field approach for purely repulsive, hard-core interactions, our theory shows that Onsager's theory is indeed valid for a reasonable range of densities.
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Schoen M, Haslam AJ, Jackson G. Perturbation Theory versus Thermodynamic Integration. Beyond a Mean-Field Treatment of Pair Correlations in a Nematic Model Liquid Crystal. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11345-11365. [PMID: 28772076 DOI: 10.1021/acs.langmuir.7b01849] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The phase behavior and structure of a simple square-well bulk fluid with anisotropic interactions is described in detail. The orientation dependence of the intermolecular interactions allows for the formation of a nematic liquid-crystalline phase in addition to the more conventional isotropic gas and liquid phases. A version of classical density functional theory (DFT) is employed to determine the properties of the model, and comparisons are made with the corresponding data from Monte Carlo (MC) computer simulations in both the grand canonical and canonical ensembles, providing a benchmark to assess the adequacy of the DFT results. A novel element of the DFT approach is the assumption that the structure of the fluid is dominated by intermolecular interactions in the isotropic fluid. A so-called augmented modified mean-field (AMMF) approximation is employed accounting for the influence of anisotropic interactions. The AMMF approximation becomes exact in the limit of vanishing density. We discuss advantages and disadvantages of the AMMF approximation with respect to an accurate description of isotropic and nematic branches of the phase diagram, the degree of orientational order, and orientation-dependent pair correlations. The performance of the AMMF approximations is found to be good in comparison with the MC data; the AMMF approximation has clear advantages with respect to an accurate and more detailed description of the fluid structure. Possible strategies to improve the DFT are discussed.
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Affiliation(s)
- Martin Schoen
- Department of Chemical Engineering, Imperial College London , South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Andrew J Haslam
- Department of Chemical Engineering, Imperial College London , South Kensington Campus, London SW7 2AZ, United Kingdom
| | - George Jackson
- Department of Chemical Engineering, Imperial College London , South Kensington Campus, London SW7 2AZ, United Kingdom
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6
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Tunable attractive interaction and the phase diagram of a system of Gay-Berne ellipsoids: A density functional approach. J Mol Liq 2016. [DOI: 10.1016/j.molliq.2016.07.115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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7
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Oyarzún Rivera B, van Westen T, Vlugt TJH. Liquid-crystal phase equilibria of Lennard-Jones chains. Mol Phys 2016. [DOI: 10.1080/00268976.2015.1134824] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
| | - Thijs van Westen
- Process and Energy Laboratory, Delft University of Technology, Delft, The Netherlands
| | - Thijs J. H. Vlugt
- Process and Energy Laboratory, Delft University of Technology, Delft, The Netherlands
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Modlińska A, Alsayed AM, Gibaud T. Condensation and dissolution of nematic droplets in dispersions of colloidal rods with thermo-sensitive depletants. Sci Rep 2015; 5:18432. [PMID: 26656207 PMCID: PMC4995677 DOI: 10.1038/srep18432] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/18/2015] [Indexed: 01/08/2023] Open
Abstract
Nematic droplets are droplets composed of elongated molecules that tend to point in the same direction but do not have any positional order. Such droplets are well known to adopt a spindle shape called tactoid. How such droplets condensate or melt and how the orientational symmetry is broken remains however unclear. Here we use a colloidal system composed of filamentous viruses as model rod-like colloids and pnipam microgel particles to induce thermo-sensitive depletion attraction between the rods. Microscopy experiments coupled to particle tracking reveal that the condensation of a nematic droplet is preceded by the formation of a new phase, an isotropic droplet. As the viruses constitute an excellent experimental realization of hard rods, it follows that the phenomenology we describe should be relevant to diverse micro- and nano-sized rods that interact through excluded volume interactions. This transition between isotropic and nematic droplets provides a new and reversible pathway to break the symmetry and order colloidal rods within a droplet with an external stimulus, and could constitute a benchmark experiment for a variety of technologies relying on reconfigurable control of rods.
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Affiliation(s)
- Anna Modlińska
- Labaroire de physique, CNRS/UMR 5672, Ecole Normale Supérieure de Lyon – Université de Lyon, 46 allée d’Italie, 69007 Lyon, France
- Faculty of Technical Physics, Poznan University of Technology, ul. Piotrowo 3, 60-965 Poznań, Poland
| | - Ahmed M. Alsayed
- Complex Assemblies of Soft Matter (COMPASS), Solvay-CNRS-UPenn UMI 3254, Bristol, Pennsylvania 19007, USA
| | - Thomas Gibaud
- Labaroire de physique, CNRS/UMR 5672, Ecole Normale Supérieure de Lyon – Université de Lyon, 46 allée d’Italie, 69007 Lyon, France
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Cinacchi G, Tani A. Isotropic–Nematic Phase Transition in Hard Platelets as Described by a Third-Virial Theory. J Phys Chem B 2015; 119:5671-6. [PMID: 25826713 DOI: 10.1021/acs.jpcb.5b00389] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Giorgio Cinacchi
- Departamento
de Física Teórica de la Materia Condensada, Instituto
de Física de la Materia Condensada (IFIMAC) and Instituto de
Ciencias de Materiales “Nicolás Cabrera”, Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid, Spain
| | - Alessandro Tani
- Dipartimento
di Chimica, Università di Pisa, Via G. Moruzzi 3, I-56124 Pisa, Italy
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Oyarzún B, van Westen T, Vlugt TJH. Isotropic-nematic phase equilibria of hard-sphere chain fluids—Pure components and binary mixtures. J Chem Phys 2015; 142:064903. [DOI: 10.1063/1.4907639] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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Wu L, Müller EA, Jackson G. Understanding and Describing the Liquid-Crystalline States of Polypeptide Solutions: A Coarse-Grained Model of PBLG in DMF. Macromolecules 2014. [DOI: 10.1021/ma401230x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Liang Wu
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Erich A. Müller
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - George Jackson
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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13
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Wu L, Jackson G, Müller EA. Liquid crystal phase behaviour of attractive disc-like particles. Int J Mol Sci 2013; 14:16414-42. [PMID: 23965962 PMCID: PMC3759919 DOI: 10.3390/ijms140816414] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 07/24/2013] [Accepted: 07/25/2013] [Indexed: 11/17/2022] Open
Abstract
We employ a generalized van der Waals-Onsager perturbation theory to construct a free energy functional capable of describing the thermodynamic properties and orientational order of the isotropic and nematic phases of attractive disc particles. The model mesogen is a hard (purely repulsive) cylindrical disc particle decorated with an anisotropic square-well attractive potential placed at the centre of mass. Even for isotropic attractive interactions, the resulting overall inter-particle potential is anisotropic, due to the orientation-dependent excluded volume of the underlying hard core. An algebraic equation of state for attractive disc particles is developed by adopting the Onsager trial function to characterize the orientational order in the nematic phase. The theory is then used to represent the fluid-phase behaviour (vapour-liquid, isotropic-nematic, and nematic-nematic) of the oblate attractive particles for varying values of the molecular aspect ratio and parameters of the attractive potential. When compared to the phase diagram of their athermal analogues, it is seen that the addition of an attractive interaction facilitates the formation of orientationally-ordered phases. Most interestingly, for certain aspect ratios, a coexistence between two anisotropic nematic phases is exhibited by the attractive disc-like fluids.
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Affiliation(s)
- Liang Wu
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; E-Mails: (L.W.); (G.J.)
| | - George Jackson
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; E-Mails: (L.W.); (G.J.)
| | - Erich A. Müller
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; E-Mails: (L.W.); (G.J.)
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14
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van Westen T, Oyarzún B, Vlugt TJH, Gross J. The isotropic-nematic phase transition of tangent hard-sphere chain fluids--pure components. J Chem Phys 2013; 139:034505. [PMID: 23883045 DOI: 10.1063/1.4815916] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An extension of Onsager's second virial theory is developed to describe the isotropic-nematic phase transition of tangent hard-sphere chain fluids. Flexibility is introduced by the rod-coil model. The effect of chain-flexibility on the second virial coefficient is described using an accurate, analytical approximation for the orientation-dependent pair-excluded volume. The use of this approximation allows for an analytical treatment of intramolecular flexibility by using a single pure-component parameter. Two approaches to approximate the effect of the higher virial coefficients are considered, i.e., the Vega-Lago rescaling and Scaled Particle Theory (SPT). The Onsager trial function is employed to describe the orientational distribution function. Theoretical predictions for the equation of state and orientational order parameter are tested against the results from Monte Carlo (MC) simulations. For linear chains of length 9 and longer, theoretical results are in excellent agreement with MC data. For smaller chain lengths, small errors introduced by the approximation of the higher virial coefficients become apparent, leading to a small under- and overestimation of the pressure and density difference at the phase transition, respectively. For rod-coil fluids of reasonable rigidity, a quantitative comparison between theory and MC simulations is obtained. For more flexible chains, however, both the Vega-Lago rescaling and SPT lead to a small underestimation of the location of the phase transition.
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Affiliation(s)
- Thijs van Westen
- Process and Energy Laboratory, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft, The Netherlands
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15
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Oyarzún B, van Westen T, Vlugt TJH. The phase behavior of linear and partially flexible hard-sphere chain fluids and the solubility of hard spheres in hard-sphere chain fluids. J Chem Phys 2013; 138:204905. [DOI: 10.1063/1.4807056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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van Westen T, Vlugt TJH, Gross J. An analytical approximation for the orientation-dependent excluded volume of tangent hard sphere chains of arbitrary chain length and flexibility. J Chem Phys 2012; 137:044906. [DOI: 10.1063/1.4737663] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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You XM, Vlasov AY, Anton L, Masters AJ. Isotropic and nematic phases of the hard spheroid fluid: a virial approach. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061706. [PMID: 23005113 DOI: 10.1103/physreve.85.061706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Indexed: 06/01/2023]
Abstract
We use a high level virial expansion to investigate the properties of the isotropic and nematic phases of the hard spheroid fluid. We use the Monte Carlo techniques described previously to calculate the virial coefficients up to seventh order and we represent the dependence of these coefficients on particle orientations via a spherical harmonic expansion. The expansion coefficients are determined using Lebedev quadrature which carries out the angular integration required exactly. For fairly spherical spheroids (1/3<a/b<3, where a and b are the semiaxes of the spheroid) the virial expansion appears to be convergent in both the isotropic and nematic phases up to high density. For more aspherical particles, the predictions varied in a more erratic fashion upon increasing the number of virials. The use of a finite angular basis set to represent the orientationally dependent virial coefficients could be a contributory cause to this.
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Affiliation(s)
- X-M You
- School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M13 9PL, United Kingdom
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18
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Dennison M, Dijkstra M, van Roij R. The effects of shape and flexibility on bio-engineered fd-virus suspensions. J Chem Phys 2012; 135:144106. [PMID: 22010697 DOI: 10.1063/1.3646951] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a theoretical model to describe binary mixtures of semi-flexible rods, applied here to fd-virus suspensions. We investigate the effects of rod stiffness on both monodisperse and binary systems, studying thick-thin and long-short mixtures. For monodisperse systems, we find that fd-virus particles have to be made extremely stiff to even approach the behavior of rigid rods. For thick-thin mixtures, we find increasingly rich phase behavior as the rods are either made more flexible or if their diameter ratio is increased. For long-short rod mixtures we find that the phase behavior is controlled by the relative stiffness of the rods, with increasing the stiffness of the long rods or decreasing that of the short rods resulting in richer phase behavior. We also calculate the state point dependent effective shape of the rods. The flexible rods studied here always behave as shorter, thicker rigid rods, but with an effective shape that varies widely throughout the phase diagrams, and plays a key role in determining phase behavior.
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Affiliation(s)
- M Dennison
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
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19
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Guevara-Rodríguez FDJ, Odriozola G. Hard ellipsoids: Analytically approaching the exact overlap distance. J Chem Phys 2011; 135:084508. [DOI: 10.1063/1.3626805] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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20
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Dennison M, Masters AJ. High-level virial theory of hard spheroids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:021709. [PMID: 21929006 DOI: 10.1103/physreve.84.021709] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 06/15/2011] [Indexed: 05/31/2023]
Abstract
We present a method for calculating high-order virial expansions of the isotropic-nematic phase transition which we apply here to hard spheroids. Studying a range of aspect ratios, for both oblate and prolate particles, we obtain equations of state, coexistence densities, and nematic order parameters, using expansions truncated at up to eighth virial level. For particles of large aspect ratios our results show rapid convergence, with truncation at sixth order sufficient to give excellent agreement with simulation data. For more spherical particles the convergence is less rapid, with results for up to eighth-order theory approaching but still not reaching simulation data. Our results indicate that high-order viral expansions are better suited to predicting equations of state than coexistence densities. We also test the validity of using the Onsager trial function to approximate the orientational distribution function, finding only small errors when making this approximation.
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Affiliation(s)
- Matthew Dennison
- School of Chemical Engineering and Analytical Science, University of Manchester, Oxford Road, Manchester M13 9PL, UK
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21
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Varga S, Jackson G. A study of steric chirality: the chiral nematic phase of a system of chiral two-site HGO molecules. Mol Phys 2011. [DOI: 10.1080/00268976.2011.556577] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Green MJ, Parra-Vasquez ANG, Behabtu N, Pasquali M. Modeling the phase behavior of polydisperse rigid rods with attractive interactions with applications to single-walled carbon nanotubes in superacids. J Chem Phys 2009; 131:084901. [DOI: 10.1063/1.3204024] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Malijevský A, Jackson G, Varga S. Many-fluid Onsager density functional theories for orientational ordering in mixtures of anisotropic hard-body fluids. J Chem Phys 2008; 129:144504. [DOI: 10.1063/1.2982501] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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28
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Bates MA, Dennison M, Masters A. Computer simulation and high level virial theory of Saturn-ring or UFO colloids. J Chem Phys 2008; 129:074901. [DOI: 10.1063/1.2969765] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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29
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Varga S, Gábor A, Velasco E, Mederos L, Vesely FJ. Demixed and ordered phases in hard-rod mixtures. Mol Phys 2008. [DOI: 10.1080/00268970802385253] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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30
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Matoz-Fernandez DA, Linares DH, Ramirez-Pastor AJ. Critical behavior of long straight rigid rods on two-dimensional lattices: Theory and Monte Carlo simulations. J Chem Phys 2008; 128:214902. [DOI: 10.1063/1.2927877] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Franco-Melgar M, Haslam AJ, Jackson G. A generalisation of the Onsager trial-function approach: describing nematic liquid crystals with an algebraic equation of state. Mol Phys 2008. [DOI: 10.1080/00268970801926958] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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32
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De Michele C, Schilling R, Sciortino F. Dynamics of uniaxial hard ellipsoids. PHYSICAL REVIEW LETTERS 2007; 98:265702. [PMID: 17678105 DOI: 10.1103/physrevlett.98.265702] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Indexed: 05/16/2023]
Abstract
We study the dynamics of monodisperse hard ellipsoids via a new event-driven molecular dynamics algorithm as a function of volume fraction phi and aspect ratio X0. We evaluate the translational D(trans) and the rotational D(rot) diffusion coefficients and the associated isodiffusivity lines in the phi-X0 plane. We observe a decoupling of the translational and rotational dynamics which generates an almost perpendicular crossing of the D(trans) and D(rot) isodiffusivity lines. While the self-intermediate scattering function exhibits stretched relaxation, i.e., glassy dynamics, only for large phi and X(0) approximately 1, the second order orientational correlator C2(t) shows stretching only for large and small X0 values. We discuss these findings in the context of a possible prenematic order driven glass transition.
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Affiliation(s)
- Cristiano De Michele
- Dipartimento di Fisica and INFM-CRS Soft, Università di Roma La Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
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33
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Cross CW, Fung BM. Molecular Dynamics Simulations for Cyanobiphenyl Liquid Crystals. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259508033553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- C. W. Cross
- a Department of Chemistry , University of Oklahoma Norman , Oklahoma , 73019-3070 , U.S.A
| | - B. M. Fung
- a Department of Chemistry , University of Oklahoma Norman , Oklahoma , 73019-3070 , U.S.A
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Affiliation(s)
- Carlos Vega
- a Departamento de Química-Física , Facultad de Ciencias Químicas, Universidad Complutense , 28040 , Madrid , Spain
| | - Santiago Lago
- a Departamento de Química-Física , Facultad de Ciencias Químicas, Universidad Complutense , 28040 , Madrid , Spain
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You XM, Vlasov AY, Masters AJ. The equation of state of isotropic fluids of hard convex bodies from a high-level virial expansion. J Chem Phys 2005; 123:34510. [PMID: 16080747 DOI: 10.1063/1.1992471] [Citation(s) in RCA: 20] [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 have calculated virial coefficients up to seventh order for the isotropic phases of a variety of fluids composed of hard aspherical particles. The models studied were hard spheroids, hard spherocylinders, and truncated hard spheres, and results are obtained for a variety of length-to-width ratios. We compare the predicted virial equations of state with those determined by simulation. We also use our data to calculate the coefficients of the y expansion [B. Barboy and W. M. Gelbart, J. Chem. Phys. 71, 3053 (1979)] and to study its convergence properties. Finally, we use our data to estimate the radius of convergence of the virial series for these aspherical particles. For fairly spherical particles, we estimate the radius of convergence to be similar to that of the density of closest packing. For more anisotropic particles, however, the radius of convergence decreases with increased anisotropy and is considerably less than the close-packed density.
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Affiliation(s)
- X-M You
- Department of Chemistry, University of Manchester, UK
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Cinacchi G, De Gaetani L, Tani A. Numerical study of a calamitic liquid-crystal model: phase behavior and structure. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 71:031703. [PMID: 15903443 DOI: 10.1103/physreve.71.031703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Indexed: 05/02/2023]
Abstract
We have studied an idealized calamitic liquid-crystal model, consisting of a linear rigid array of nine soft repulsive spheres, employing both theory and molecular dynamics simulation. The phase behavior (which includes crystalline, smectic, nematic, and isotropic phases) and structure of a collection of these rodlike particles have been determined by molecular dynamics simulation in an isothermal-isobaric ensemble. The liquid crystalline part of the phase diagram has been compared to that emerging from an Onsager-type density-functional theory. We have found a fair agreement between theory and computer simulation results, with a similar accuracy for the smectic to nematic and nematic to isotropic phase transitions.
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de Miguel E, Martı́n del Rı́o E. Equation of state for hard Gaussian overlap fluids. J Chem Phys 2003. [DOI: 10.1063/1.1531611] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Varga S, Szalai I, Liszi J, Jackson G. A study of orientational ordering in a fluid of dipolar Gay–Berne molecules using density-functional theory. J Chem Phys 2002. [DOI: 10.1063/1.1469607] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Syvitski RT, Burnell EE. Dipole-induced ordering in nematic liquid crystals. II. The elusive holy grail. J Chem Phys 2000. [DOI: 10.1063/1.1287336] [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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Varga S, Kronome G, Szalai I. External field induced tricritical phenomenon in the isotropicnematic phase transition of hard non-spherical particle systems. Mol Phys 2000. [DOI: 10.1080/00268970050032765] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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VARGA SZABOLCS, WILLIAMSON DAVEC, SZALAI ISTVÁN. Square-well fluid based decoupling approximation for system of hard non-spherical particles with spherical square-wells. Mol Phys 1999. [DOI: 10.1080/00268979909483113] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Burnell EE, de Lange CA. Prediction from Molecular Shape of Solute Orientational Order in Liquid Crystals. Chem Rev 1998; 98:2359-2388. [PMID: 11848965 DOI: 10.1021/cr941159v] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- E. E. Burnell
- Laboratory for Physical Chemistry, University of Amsterdam, Nieuwe Achtergracht 127-129, 1018 WS Amsterdam, The Netherlands
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Padilla P, Velasco E. The isotropic–nematic transition for the hard Gaussian overlap fluid: Testing the decoupling approximation. J Chem Phys 1997. [DOI: 10.1063/1.474075] [Citation(s) in RCA: 43] [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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Camp PJ, Allen MP, Bolhuis PG, Frenkel D. Demixing in hard ellipsoid rod-plate mixtures. J Chem Phys 1997. [DOI: 10.1063/1.474012] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Camp PJ, Mason CP, Allen MP, Khare AA, Kofke DA. The isotropic–nematic phase transition in uniaxial hard ellipsoid fluids: Coexistence data and the approach to the Onsager limit. J Chem Phys 1996. [DOI: 10.1063/1.472146] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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McGrother SC, Williamson DC, Jackson G. A re‐examination of the phase diagram of hard spherocylinders. J Chem Phys 1996. [DOI: 10.1063/1.471343] [Citation(s) in RCA: 307] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Komolkin AV, Maliniak A. Local structure in anisotropic systems determined by molecular dynamics simulation. Mol Phys 1995. [DOI: 10.1080/00268979500100851] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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