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SUMMARY:Ho-Kei Chan - Confinement-induced Columnar Crystals: A Route to Ne
 w Architecture in the Scientific World - Ho-Kei  Chan (Harbin Institute of
  Technology)
DTSTART:20230817T090000Z
DTEND:20230817T100000Z
UID:TALK204082@talks.cam.ac.uk
DESCRIPTION:Identical spheres in cylindrical confinement exhibit a complex
  variety of densest-packed columnar structures. Such densest-packed struct
 ures can serve as theoretical models for the structures of a variety of qu
 asi-one-dimensional physical systems\, such as nanotube-confined fullerene
 s\, nanochannel-confined copolymers\, colloidal crystal wires\, capillary-
 tube-confined thermoresponsive microspheres\, capillary-tube-confined micr
 obubbles\, and fluid-driven self-assemblies of polymer beads. On the other
  hand\, there have been comparatively few studies of this kind for shape-a
 nisotropic particles. Thanks to their rotational degrees of freedom\, shap
 e-anisotropic particles in cylindrical confinement exhibit densest-packed 
 structures with non-trivial orientational order\, and therefore they demon
 strate a greater variety of densest-packed crystal structures than their s
 pherical counterparts.\nIn this talk\, I will present a historical overvie
 w of research on the densest-packed structures of identical hard spheres i
 n cylindrical confinement\, and then present our recent extensions of such
  research to shape-anisotropic particles and polydisperse systems. For pac
 kings of spheres\, I will introduce a variety of columnar crystals as disc
 overed computationally in the past two decades\, and explain how a wide ra
 nge of such structures can be obtained through a method of sequential depo
 sition. I will also discuss how some ordered but non-densest crystal struc
 tures can be discovered through this specific method of sequential deposit
 ion. For packings of shape-anisotropic particles\, I will present a variet
 y of densest-packed columnar crystals as discovered recently for identical
  spheroids in cylindrical confinement and for identical ellipses within a 
 parallel strip. For the case of spheroids\, I will explain how the corresp
 onding densest-packed structures arise from a competition between confinem
 ent-induced chiral ordering and shape-anisotropy-induced orientational ord
 ering. For the case of ellipses\, I will explain why the corresponding den
 sest-packed structures are all affine transformations of particular denses
 t-packed structures of circular disks. For packings of polydisperse partic
 les\, I will explain how the corresponding densest-packed zigzag structure
 s arise from a size segregation of particles in quasi-1D confinement. It i
 s believed that the confinement-induced crystal structures presented in th
 is talk could constitute a basis for the development of novel low-dimensio
 nal materials with tailored translational or orientational order.
LOCATION:External
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