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SUMMARY:Thermodynamically Stable Quasicrystal and Dense Dimer Packings fro
 m Tetrahedron Colloids - Michael Engel (Friedrich-Alexander-Universität E
 rlangen-Nürnberg)
DTSTART:20230823T090000Z
DTEND:20230823T093000Z
UID:TALK202618@talks.cam.ac.uk
DESCRIPTION:The tetrahedral geometry is ubiquitous in natural and syntheti
 c systems. Regular tetrahedra do not tile space\, which makes understandin
 g their self-assembly behavior a formidable challenge. Simulations of hard
  tetrahedra &ndash\;that is particles with the shape of a regular tetrahed
 ron interacting only by excluded volume interactions&ndash\; discovered a 
 dodecagonal quasicrystal stabilized by entropy alone [1]. But while this q
 uasicrystal forms robustly and reproducibly in simulation\, it competes wi
 th periodic approximants and cannot be the thermodynamic ground state in t
 he limit of infinite pressure. In this limit\, the densest packing will ev
 entually prevail\, which is a simple (in comparison) dimer crystal [2].\nH
 ere\, we advance research on tetrahedron particles in two directions. Firs
 t\, we demonstrate that the quasicrystal is thermodynamically stable at in
 termediate density [3]. Using a pattern recognition algorithm applied to p
 article trajectories during quasicrystal growth\, we analyse phason strain
  to follow the evolution of quasiperiodic order. Our results demonstrate t
 hat soft-matter quasicrystals dominated by entropy can be thermodynamicall
 y stable and grown with high structural quality&ndash\;&ndash\;just like t
 heir more common alloy quasicrystal counterparts.\nSecond\, we discuss exp
 erimental realizations of phases of tetrahedron colloids where vertex shar
 pness\, surface ligands\, and the self-assembly environment play key roles
  in the formation of the quasicrystal and the dimer crystal [4]. We fully 
 resolve the complex three-dimensional structure of the quasicrystal by a c
 ombination of electron microscopy\, tomography\, and synchrotron X-ray sca
 ttering. Our findings demonstrate the predictive power of computer simulat
 ions as well as the importance of accurate control over nanocrystal attrib
 utes and the assembly method to realize increasingly complex nanopolyhedro
 n supracrystals.\n[1] A. Haji-Akbari\, M. Engel\, A.S. Keys\, X. Zheng\, R
 .G. Petschek\, P. Palffy-Muhoray\, S.C.&nbsp\;Glotzer\, Nature 462 (2009) 
 773.\n[2] E.R. Chen\, M. Engel\, S.C. Glotzer\, D. Comput. Geom. 44 (2010)
 \, 253.\n[3] K. Je\, S. Lee\, E.G. Teich\, M. Engel\, S.C. Glotzer\, Proc.
  Natl. Acad. Sci. 118 (2021) e2011799118.\n[4] Y. Wang\, J. Chen\, R. Li\,
  A. G&ouml\;tz\, D. Drobek\, T. Przybilla\, S. H&uuml\;bner\, P. Pelz\, L.
  Yang\, B. Apeleo Zubiri\, E. Spiecker\, M. Engel\, X. Ye\, JACS\, in pres
 s (2023).
LOCATION:External
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