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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2022
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2211.08109 |
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| _version_ | 1866913435839627264 |
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| author | Longa, Lech Cieśla, Michał Karbowniczek, Paweł Chrzanowska, Agnieszka |
| author_facet | Longa, Lech Cieśla, Michał Karbowniczek, Paweł Chrzanowska, Agnieszka |
| contents | We study the self-organization of flexible planar trimer particles on a structureless surface. The molecules are made up of two mesogenic units linked by a spacer, all of which are modeled as hard needles of the same length. Each molecule can dynamically adopt two conformational states: an achiral bent-shaped (cis-) and a chiral zigzag (trans-) one.
Using constant pressure Monte Carlo simulations and Onsager-type density functional theory (DFT), we show that the system consisting of these molecules exhibits a rich spectrum of (quasi-)liquid crystalline phases. The most interesting observation is the identification of stable smectic splay-bend ($S_{SB}$) and chiral smectic A ($S_A^*$) phases. The $S_{SB}$ phase is also stable in the limit, where only cis-conformers are allowed. The second phase occupying a considerable portion of the phase diagram is $S_A^*$ with chiral layers, where the chirality of the neighboring layers is of opposite sign. The study of the average fractions of the trans- and cis-conformers in various phases shows that while in the isotropic phase all fractions are equally populated, the $S_A^*$ phase is dominated by chiral conformers (zigzag), but the achiral conformers win in the smectic splay-bend phase. To clarify the possibility of stabilization of the nematic splay bend ($N_{SB}$) phase for trimers, the free energy of the $N_{SB}$ and $S_{SB}$ phases is calculated within DFT for the cis-conformers, for densities where simulations show stable $S_{SB}$. It turns out that the $N_{SB}$ phase is unstable away from the phase transition to the nematic phase, and its free energy is always higher than that of $S_{SB}$, down to the transition to the nematic phase, although the difference in free energies becomes extremely small when approaching the transition. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2211_08109 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Conformational degrees of freedom and stability of splay-bend ordering in the limit of a very strong planar anchoring Longa, Lech Cieśla, Michał Karbowniczek, Paweł Chrzanowska, Agnieszka Soft Condensed Matter We study the self-organization of flexible planar trimer particles on a structureless surface. The molecules are made up of two mesogenic units linked by a spacer, all of which are modeled as hard needles of the same length. Each molecule can dynamically adopt two conformational states: an achiral bent-shaped (cis-) and a chiral zigzag (trans-) one. Using constant pressure Monte Carlo simulations and Onsager-type density functional theory (DFT), we show that the system consisting of these molecules exhibits a rich spectrum of (quasi-)liquid crystalline phases. The most interesting observation is the identification of stable smectic splay-bend ($S_{SB}$) and chiral smectic A ($S_A^*$) phases. The $S_{SB}$ phase is also stable in the limit, where only cis-conformers are allowed. The second phase occupying a considerable portion of the phase diagram is $S_A^*$ with chiral layers, where the chirality of the neighboring layers is of opposite sign. The study of the average fractions of the trans- and cis-conformers in various phases shows that while in the isotropic phase all fractions are equally populated, the $S_A^*$ phase is dominated by chiral conformers (zigzag), but the achiral conformers win in the smectic splay-bend phase. To clarify the possibility of stabilization of the nematic splay bend ($N_{SB}$) phase for trimers, the free energy of the $N_{SB}$ and $S_{SB}$ phases is calculated within DFT for the cis-conformers, for densities where simulations show stable $S_{SB}$. It turns out that the $N_{SB}$ phase is unstable away from the phase transition to the nematic phase, and its free energy is always higher than that of $S_{SB}$, down to the transition to the nematic phase, although the difference in free energies becomes extremely small when approaching the transition. |
| title | Conformational degrees of freedom and stability of splay-bend ordering in the limit of a very strong planar anchoring |
| topic | Soft Condensed Matter |
| url | https://arxiv.org/abs/2211.08109 |