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Brumby PE, Kowaguchi A, Nozawa T, Yasuoka K, Wensink HH. Pre-Smectic Ordering and the Unwinding Helix in Monte Carlo Simulations of Cholesteric Liquid-Crystals. J Phys Chem B 2023; 127:7194-7204. [PMID: 37540189 DOI: 10.1021/acs.jpcb.3c02018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
In this paper, molecular chirality is studied for liquid-crystal fluids represented by hard rods with the addition of an attractive chiral dispersion term. Chiral forces between molecular pairs are assumed to be long-ranged and are described in terms of the pseudotensor of Goossens [W. J. A. Goossens, Mol. Cryst. Liq. Cryst. 1971, 12, 237-244]. Following Varga and Jackson [S. Varga and G. Jackson, Chem. Phys. Lett. 2003, 377, 6-12], this is combined with a hard-spherocylinder core. We investigate the relationship between molecular chirality and the helical pitch of the system, which occurs in the absence of full three-dimensional periodic boundary conditions. The dependence of the wavenumber of this pitch on the thermodynamic variables, temperature, and density is measured. We also explore the use of a novel surface boundary interaction model. As a result of this approach, we are able to lower the temperature of the system without the occurrence of nematic droplets, which would interfere with the formation of a uniaxial pitch. Regarding the theoretical predictions of Wensink and Jackson [H. H. Wensink and G. Jackson, J. Chem. Phys. 2009, 130, 234911], on the one hand, we have qualitative agreement with the observed non-monotonic density dependence of the wavenumber. Initially increasing with density, the wavenumber reaches a maximum, before falling as the density moves toward the point of phase transition from cholesteric to smectic. However, further analysis for shorter rods, in the presence of novel boundary conditions, reveals some disagreement with the theory, at least in this case; the unwinding of the cholesteric helix in the cholesteric phase occurs simultaneously with subtle increases in smectic ordering. These pre-smectic fluctuations have not been accounted for so far in theories on cholesterics but turn out to play a key role in controlling the pitch of cholesteric phases of rod-shaped mesogens with a small to moderate aspect ratio.
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Affiliation(s)
- Paul E Brumby
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Akie Kowaguchi
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Takuma Nozawa
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Kenji Yasuoka
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Henricus H Wensink
- Laboratoire de Physique des Solides─UMR 8502, Université Paris-Saclay & CNRS, Orsay 91405, France
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Wu L, Sun H. Manipulation of cholesteric liquid crystal phase behavior and molecular assembly by molecular chirality. Phys Rev E 2019; 100:022703. [PMID: 31574769 DOI: 10.1103/physreve.100.022703] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Indexed: 06/10/2023]
Abstract
Molecular simulation is used to study the effect of molecular chirality on liquid crystalline phase transition and molecular assembly behavior. Based on a flexible chain (FCh) model with helical arrangement of side beads, the phase behavior of FCh models with various molecular chiralities are studied as functions of pressure (or density). By modifying the molecular chirality of FCh, we can manipulate the relative stability of the nematic and cholesteric phases continuously; and we found that increasing molecular chirality may destabilize cholesteric order due to the effective reduction of chiral interactions. A semismectic phase is identified in the high-density region, in which the two-dimensional fluid layers overlap due to shift alignment formed by FCh particles. The global phase diagram of the FCh model is constructed and the potential energy surface is calculated to elucidate the formation of cholesteric phase in terms of two-body interactions.
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Affiliation(s)
- Liang Wu
- School of Chemistry and Chemical Engineering, Materials Genome Initiative Center, and Key Laboratory of Scientific and Engineering Computing of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Huai Sun
- School of Chemistry and Chemical Engineering, Materials Genome Initiative Center, and Key Laboratory of Scientific and Engineering Computing of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240, China
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Tortora MMC, Doye JPK. Hierarchical bounding structures for efficient virial computations: Towards a realistic molecular description of cholesterics. J Chem Phys 2018; 147:224504. [PMID: 29246043 DOI: 10.1063/1.5002666] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We detail the application of bounding volume hierarchies to accelerate second-virial evaluations for arbitrary complex particles interacting through hard and soft finite-range potentials. This procedure, based on the construction of neighbour lists through the combined use of recursive atom-decomposition techniques and binary overlap search schemes, is shown to scale sub-logarithmically with particle resolution in the case of molecular systems with high aspect ratios. Its implementation within an efficient numerical and theoretical framework based on classical density functional theory enables us to investigate the cholesteric self-assembly of a wide range of experimentally relevant particle models. We illustrate the method through the determination of the cholesteric behavior of hard, structurally resolved twisted cuboids, and report quantitative evidence of the long-predicted phase handedness inversion with increasing particle thread angles near the phenomenological threshold value of 45°. Our results further highlight the complex relationship between microscopic structure and helical twisting power in such model systems, which may be attributed to subtle geometric variations of their chiral excluded-volume manifold.
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Affiliation(s)
- Maxime M C Tortora
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Jonathan P K Doye
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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Tortora MMC, Doye JPK. Perturbative density functional methods for cholesteric liquid crystals. J Chem Phys 2017. [DOI: 10.1063/1.4982934] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Maxime M. C. Tortora
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Jonathan P. K. Doye
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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De Michele C, Zanchetta G, Bellini T, Frezza E, Ferrarini A. Hierarchical Propagation of Chirality through Reversible Polymerization: The Cholesteric Phase of DNA Oligomers. ACS Macro Lett 2016; 5:208-212. [PMID: 35614680 DOI: 10.1021/acsmacrolett.5b00579] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Unveiling the subtle rules that control the buildup of macroscopic chirality starting from chiral molecular elements is a challenge for theory and computations. In this context, a remarkable phenomenon is the formation of helically twisted nematic (cholesteric) phases, with pitch in the micrometer range, driven by self-assembly of relatively small chiral species into supramolecular semiflexible polymers. We have developed a theoretical framework to connect the cholesteric organization to the shape and chirality of the constituents, described with molecular detail, in this kind of system. The theory has been tested against new accurate measurements for solutions of short DNA duplexes. We show that the cholesteric organization is determined by steric repulsion between duplexes, and we identify distinctive features of linear self-assembly in the temperature and concentration dependence of the pitch.
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Affiliation(s)
- Cristiano De Michele
- Dipartimento
di Fisica, “Sapienza” Università di Roma, P.le A. Moro
2, 00185 Roma, Italy
| | - Giuliano Zanchetta
- Dipartimento
di Biotecnologie Mediche e Medicina Traslazionale, Università di Milano, via F.lli Cervi 93, Segrate (MI), Italy
| | - Tommaso Bellini
- Dipartimento
di Biotecnologie Mediche e Medicina Traslazionale, Università di Milano, via F.lli Cervi 93, Segrate (MI), Italy
| | - Elisa Frezza
- Dipartimento
di Scienze Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
| | - Alberta Ferrarini
- Dipartimento
di Scienze Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
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Wensink HH, Morales-Anda L. Chiral assembly of weakly curled hard rods: Effect of steric chirality and polarity. J Chem Phys 2015; 143:144907. [DOI: 10.1063/1.4932979] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- H. H. Wensink
- Laboratoire de Physique des Solides–UMR 8502, Université Paris-Sud & CNRS, 91405 Orsay, France
| | - L. Morales-Anda
- Laboratoire de Physique des Solides–UMR 8502, Université Paris-Sud & CNRS, 91405 Orsay, France
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Dussi S, Belli S, van Roij R, Dijkstra M. Cholesterics of colloidal helices: Predicting the macroscopic pitch from the particle shape and thermodynamic state. J Chem Phys 2015; 142:074905. [DOI: 10.1063/1.4908162] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Simone Dussi
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Simone Belli
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
| | - René van Roij
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
| | - Marjolein Dijkstra
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
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Belli S, Dussi S, Dijkstra M, van Roij R. Density functional theory for chiral nematic liquid crystals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:020503. [PMID: 25215676 DOI: 10.1103/physreve.90.020503] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Indexed: 06/03/2023]
Abstract
Even though chiral nematic phases were the first liquid crystals experimentally observed more than a century ago, the origin of the thermodynamic stability of cholesteric states is still unclear. In this Rapid Communication we address the problem by means of a density functional theory for the equilibrium pitch of chiral particles. When applied to right-handed hard helices, our theory predicts an entropy-driven cholesteric phase, which can be either right or left handed, depending not only on the particle shape but also on the thermodynamic state. We explain the origin of the chiral ordering as an interplay between local nematic alignment and excluded-volume differences between left- and right-handed particle pairs.
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Affiliation(s)
- S Belli
- Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
| | - S Dussi
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - M Dijkstra
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - R van Roij
- Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
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Frezza E, Ferrarini A, Bindu Kolli H, Giacometti A, Cinacchi G. Left or right cholesterics? A matter of helix handedness and curliness. Phys Chem Chem Phys 2014; 16:16225-32. [DOI: 10.1039/c4cp01816h] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Using an Onsager-like theory, we have investigated the relationship between the morphology of hard helical particles and the features (pitch and handedness) of the cholesteric phase that they form.
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Affiliation(s)
- Elisa Frezza
- Dipartimento di Scienze Chimiche
- Università di Padova
- 35131 Padova, Italy
| | - Alberta Ferrarini
- Dipartimento di Scienze Chimiche
- Università di Padova
- 35131 Padova, Italy
| | - Hima Bindu Kolli
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- 30123 Venezia, Italy
| | - Achille Giacometti
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- 30123 Venezia, Italy
| | - Giorgio Cinacchi
- Departamento de Física Teórica de la Materia Condensada and Instituto de Física de la Materia Condensada
- Universidad Autónoma de Madrid
- Campus de Cantoblanco
- 28049 Madrid, Spain
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