Molecular dynamics simulation study of two-dimensional diffusion behavior in smectic liquid crystalline monolayers

Go Watanabe, Jun Ichi Saito, Yusuke Fujita, Yuka Tabe

    Research output: Contribution to journalArticle

    3 Citations (Scopus)

    Abstract

    We have carried out molecular dynamics (MD) simulations for monolayers of smectic A and C liquid crystal (LC) phases in order to investigate the in-plane molecular diffusion from the microscopic point of view. In contrast to similar complex two-dimensional systems (e.g., biomembranes) whose molecular diffusion is anomalous, in-plane mean square displacements (MSDs) for both phases increase linearly with passing time similar to typical fluids on the nanosecond time scale. By following the relation between the diffusion and the viscosity in the fluids, we estimated the viscosity coefficients for both LC monolayers, and the obtained values indicate that the smectic A monolayer has a higher viscosity than the smectic C one. Moreover, we investigate the in-plane self-diffusion anisotropy Dk=D? for smectic C and found that the diffusion parallel to the molecular tilt is 1.5 times larger than that in the perpendicular direction. This anisotropic diffusion property in the smectic C monolayer has not been clearly confirmed thus far.

    Original languageEnglish
    Article number084603
    JournalJournal of the Physical Society of Japan
    Volume82
    Issue number8
    DOIs
    Publication statusPublished - 2013 Aug

    Fingerprint

    molecular diffusion
    viscosity
    molecular dynamics
    liquids
    liquid crystals
    simulation
    fluids
    anisotropy
    coefficients

    Keywords

    • Langmuir monolayers
    • Liquid crystals
    • Molecular dynamics
    • Phase Transition
    • Two-dimensional diffusion property

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

    Cite this

    Molecular dynamics simulation study of two-dimensional diffusion behavior in smectic liquid crystalline monolayers. / Watanabe, Go; Saito, Jun Ichi; Fujita, Yusuke; Tabe, Yuka.

    In: Journal of the Physical Society of Japan, Vol. 82, No. 8, 084603, 08.2013.

    Research output: Contribution to journalArticle

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    AU - Saito, Jun Ichi

    AU - Fujita, Yusuke

    AU - Tabe, Yuka

    PY - 2013/8

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    N2 - We have carried out molecular dynamics (MD) simulations for monolayers of smectic A and C liquid crystal (LC) phases in order to investigate the in-plane molecular diffusion from the microscopic point of view. In contrast to similar complex two-dimensional systems (e.g., biomembranes) whose molecular diffusion is anomalous, in-plane mean square displacements (MSDs) for both phases increase linearly with passing time similar to typical fluids on the nanosecond time scale. By following the relation between the diffusion and the viscosity in the fluids, we estimated the viscosity coefficients for both LC monolayers, and the obtained values indicate that the smectic A monolayer has a higher viscosity than the smectic C one. Moreover, we investigate the in-plane self-diffusion anisotropy Dk=D? for smectic C and found that the diffusion parallel to the molecular tilt is 1.5 times larger than that in the perpendicular direction. This anisotropic diffusion property in the smectic C monolayer has not been clearly confirmed thus far.

    AB - We have carried out molecular dynamics (MD) simulations for monolayers of smectic A and C liquid crystal (LC) phases in order to investigate the in-plane molecular diffusion from the microscopic point of view. In contrast to similar complex two-dimensional systems (e.g., biomembranes) whose molecular diffusion is anomalous, in-plane mean square displacements (MSDs) for both phases increase linearly with passing time similar to typical fluids on the nanosecond time scale. By following the relation between the diffusion and the viscosity in the fluids, we estimated the viscosity coefficients for both LC monolayers, and the obtained values indicate that the smectic A monolayer has a higher viscosity than the smectic C one. Moreover, we investigate the in-plane self-diffusion anisotropy Dk=D? for smectic C and found that the diffusion parallel to the molecular tilt is 1.5 times larger than that in the perpendicular direction. This anisotropic diffusion property in the smectic C monolayer has not been clearly confirmed thus far.

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