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The "magic" angle in the self-assembly of colloids suspended in a nematic host phase

2014/02/28 by Sergej Schlotthauer, Tillmann Stieger, Schlotthauer, Sergej +7
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Liquid Crystal Research Advancements #Material Dynamics and Properties #Photonic Crystals and Applications #Soft Condensed Matter (cond-mat.soft) #cond-mat.soft

paper · pdf · doi:10.48550/arxiv.1402.7165

openalex publication_date 2014/02/28 · arxiv created 2015/05/21 · arxiv updated 2015/05/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Using extensive Monte Carlo (MC) simulations of colloids immersed in a nematic liquid crystal we compute an effective interaction potential via the local nematic director field and its associated order parameter. The effective potential consists of a local Landau-de Gennes (LdG) and a Frank elastic contribution. Molecular expressions for the LdG expansion coefficients are obtained via classical density functional theory (DFT). The DFT result for the LdG parameter A is improved by locating the phase transition through finite-size scaling theory. We consider effective interactions between a pair of homogeneous colloids with Boojum defect topology. In particular, colloids attract each other if the angle between their center-of-mass distance vector and the far-field nematic director is about 30 which settles a long-standing discrepancy between theory and experiment. Using the effective potential in two-dimensional MC simulations we show that self-assembled structures formed by the colloids are in excellent agreement with experimental data.

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