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SUMMARY:Phases of passive and active matter in two dimensions - Leticia Cu
 gliandolo\, LPTHE Sorbonne-Jussieu
DTSTART:20200225T130000Z
DTEND:20200225T140000Z
UID:TALK136189@talks.cam.ac.uk
CONTACT:Professor Mike Cates
DESCRIPTION:Long-range translational order is forbidden in low dimensional
  systems\nwith short-range interactions\, and solid phases only have\nquas
 i long-range translational order in two dimensions. A mechanism for\nthe t
 ransition from solid to liquid led by the dissociation of dislocation\npai
 rs was proposed by Kosterlitz & Thouless in their 1972 & 1973 Nobel\nprize
  papers. Knowing that long-range orientational order is possible in\ntwo d
 imensions\, Nelson\, Halperin and Young argued  that the transition\nactua
 lly occurs in two steps\, the second one being triggered by  the\nunbindin
 g of disclinations. In this picture the intermediate phase keeps\nquasi lo
 ng-range orientational order\, and the two transitions are of\ninfinite or
 der. Based on simulations of hard disks\, Bernard & Krauth\nrecently conte
 sted the latter picture. In this talk I will briefly review\nall these iss
 ues and I will extend their analysis to systems of\nself-propelled particl
 es\, the constituents of active matter\, a new kind of\nsoft matter releva
 nt to describe numerous biological problems. In\nparticular\, I will discu
 ss in detail the phase diagram of active Brownian\nparticles and the role 
 played by topological effects in all the\ntransitions found.\n\nThe refere
 nces are\n\nClustering of topological defects in two-dimensional melting o
 f active and\npassive disks\n Pasquale Digregorio\, Demian Levis\, Leticia
  F. Cugliandolo\, Giuseppe\nGonnella\, Ignacio Pagonabarraga\narXiv:1911.0
 6366\n\nFull phase diagram of active Brownian disks: from melting to\nmoti
 lity-induced phase separation\nPasquale Digregorio\, Demian Levis\, Antoni
 o Suma\, Leticia F. Cugliandolo\,\nGiuseppe Gonnella\, Ignacio Pagonabarra
 ga\narXiv:1805.12484\, Phys. Rev. Lett. 121\, 098003 (2018)\n
LOCATION:MR11\, CMS
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