IJS KOLOKVIJ, sreda, 26. 6. 2019, ob 13.00 uri, prof. dr. Emanuela Zaccarelli

[Natasa Gosevac]

Vabimo vas na 19. predavanje iz sklopa "Kolokviji na IJS" v letu 2018/19, ki bo v sredo, 26. junija 2019, ob 13 uri v Veliki predavalnici Instituta »Jožef Stefan«  na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na http://videolectures.net/kolokviji_ijs.
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prof. dr. Emanuela Zaccarelli
National Research Council – Institute for Complex Systems and Department of Physics, Sapienza University of Rome, Rim, Italija
 
Mikroskopska vloga deformacije pri dinamiki mehkih koloidov
 
Mehki koloidi omogočajo raziskovanje stanj z gostotami, ki presegajo gostoto naključnega tesnega sklada, a doslej je le malo znanega o tem, kako mehkost delcev vpliva na dinamiko pri tako velikih gostotah. Eksperimentalne študije dajejo protislovne odgovore in numerične raziskave so se doslej osredotočale prvenstveno na preproste modele, ki omogočajo prekrivanje delcev, a zanemarijo deformacijo. Zato je koncept mehkosti v simulacijah težko primerljiv s tistim, s katerim imamo opravka v eksperimentih. Tu obravnavamo modelski sistem, ki sestoji iz polimernih obročev z notranjo elastičnostjo. Pri velikih polnilnih razmerjih kaže ta sistem komprimirano eksponentno pojemanje intermediarnih sipalnih funkcij in superdifuzivno obnašanje povprečnega odmika delcev. Te lastnosti lahko pojasnimo s kompleksnim prepletom deformacije delcev in dinamične heterogenosti, ki vodi do persistenčnega gibanja balističnih delcev. Opazimo tudi izrazito variacijo relaksacijskih časov z naraščajočo velikostjo delcev, kar jasno kaže na bistveno vlogo deformacije pri dinamiki realnih mehkih koloidov.
Predavanje bo v angleščini.

Lepo vabljeni!
 
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We invite you to the 19th Institute colloquium in the academic year 2018/19. The colloquium will be held on Wednesday, June 26, 2019 at 13 PM in the main Institute lecture hall, Jamova 39, Ljubljana. To read the abstract click  http://www.ijs.si/ijsw/Koledar_prireditev. Past colloquia are posted on  http://videolectures.net/kolokviji_ijs.
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prof. dr. Emanuela Zaccarelli
prof. dr. Emanuela Zaccarelli, National Research Council – Institute for Complex Systems and Department of Physics, Sapienza University of Rome, Rome, Italy
 
The microscopic role of deformation in the dynamics of soft colloids
 
Soft colloids enable the exploration of states with densities exceeding that of random close packing, but it remains unclear whether softness controls the dynamics under these dense conditions. Experimental studies have reported conflicting results, and numerical studies have so far focused primarily on simple models that allow particles to overlap, but neglect particle deformations. This makes the concept of softness in simulations and experiments difficult to compare. Here, we propose a model system consisting of polymer rings with internal elasticity. At high packing fractions, the system displays compressed exponential decay of the intermediate scattering functions and super-diffusive behaviour of the mean-squared displacements. These features are explained in terms of the complex interplay between particle deformations and dynamic heterogeneities, which gives rise to persistent motion of ballistic particles. We also observe a striking variation of the relaxation times with increasing particle softness, clearly demonstrating the crucial role of deformation in the dynamics of realistic soft colloids.
 
Cordially invited!
 
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