Cuetos, Alejandro

Profesor/a Titular de Universidad
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First Name
Last Name
Universidad Pablo de Olavide
Sistemas Físicos, Químicos y Naturales
Research Center
Química Física
Research Group
Física Estadística de Líquidos
Física, Química y Matemáticas
PhD programs
Simulación Molecular de Sistemas Complejos con Aplicaciones Medioambientales, Tecnología Química y de Materialea
UPO investigaORCIDScopus Author IDWeb of Science ResearcherIDDialnet IDGoogle Scholar ID

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Now showing 1 - 3 of 3
  • Publication
    Dynamics of hard colloidal cuboids in nematic liquid crystals
    (American Physical Society, 2020) Cuetos, Alejandro; Patti, Alessandro
    We perform dynamic Monte Carlo simulations to investigate the equilibrium dynamics of hard board-like colloidal particles in oblate and prolate nematic liquid crystals. In particular, we characterize the particles' diffusion along the nematic director and perpendicularly to it, and observe a structural relaxation decay that strongly depends on the particle anisotropy. To assess the Gaussianity of their dynamics and eventual occurrence of collective motion, we calculate two- and four-point correlation functions that incorporate the instantaneous values of the diffusion coefficients parallel and perpendicular to the nematic director. Our simulation results highlight the occurrence of Fickian and Gaussian dynamics at short and long times, locate the minimum diffusivity at the self-dual shape, the particle geometry that would preferentially stabilise biaxial nematics, and exclude the existence of dynamically correlated particles.
  • Publication
    Brownian dynamics simulations of oblate and prolate colloidal particles in nematic liquid crystals
    (AIP, 2019) Morillo, Neftalí; Patti, Alessandro; Cuetos, Alejandro
    It is well known that understanding the transport properties of liquid crystals is crucial to optimize their performance in a number of technological applications. In this work, we analyze the effect of shape anisotropy on the diffusion of rodlike and disklike particles by Brownian dynamics simulations. To this end, we compare the dynamics of prolate and oblate nematic fluids incorporating particles with the same infinite-dilution translational or rotational diffusion coefficients. Under these conditions, which are benchmarked against the standard case of identical aspect ratios, we observe that prolate particles display faster dynamics than oblate particles at short and long time scales. Nevertheless, when compared at identical infinite-dilution translational diffusion coefficients, oblate particles are faster than their prolate counterparts at short-to-intermediate time scales, which extend over almost three time decades. Both oblate and prolate particles exhibit an anisotropic diffusion with respect to the orientation of the nematic director. More specifically, prolate particles show a fast diffusion in the direction parallel to the nematic director, while their diffusion in the direction perpendicular to it is slower. By contrast, the diffusion of oblate particles is faster in the plane perpendicular to the nematic director. Finally, in the light of our recent study on the long-time Gaussian and Fickian diffusion in nematic systems, we map the decay of the autocorrelation functions and their fluctuations over the time scales of our simulations to ponder the existence of mobile clusters of particles and the occurrence of collective motion.
  • Publication
    Dynamics in field-induced biaxial nematic liquid crystals of board-like particles
    (Elsevier, 2022-12) Rodríguez Rivas, Álvaro; Patti, Alessandro; Cuetos, Alejandro
    Biaxial nematic (NB) liquid crystals have been indicated as promising candidates for the design of next- generation displays with novel electro-optical properties and faster switching times. While at the molecular scale their existence is still under debate, experimental evidence, supported by theory and simulation, has unambiguously proved that suitable colloidal particles can indeed form NB fluids under specific conditions. While this discovery has sparked a widespread interest in the characterisation of the phase behaviour of NB liquid crystals, significantly less attention has been devoted to the study of their transport properties. To bridge this gap, by Dynamic Monte Carlo simulations we have investigated the equilibrium dynamics of field-induced NB phases comprising monodisperse hard cuboids. In particular, we calculated the long-time self-diffusion coefficients of cuboids over a wide range of anisotropies, spanning prolate to oblate geometries. Additionally, we have compared these diffusivities with those that, upon switching the external field off, are measured in the thermodynamically-stable isotropic or uniaxial nematic phases at the same density. Our results indicate that while prolate cuboids diffuse significantly faster in biaxial nematics than in less ordered fluids, we do not observe such an increase with oblate cuboids at high packing fractions. We show that these changes are most likely due to the field-induced freezing of the axes perpendicular to the nematic director, along with a substantial increase in the ordering of the resulting NB phase.