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Seminare - Sommer Semester 2017

Seminar über "spezielle Probleme in der Theorie der Kolloide"

Ort: HHU Düsseldorf, Seminarraum 25.32.O2.51
Programm:
DatumSprecher/inThemaZeit
Mi 03.05.2017   G. Pessot  Self-induced polar order for pushers and pullers  13:30 s.t.
Mo 08.05.2017   C. Hoell  Dynamical density functional theory for circle swimmers  14:30 s.t.
Mi 10.05.2017   C. Sitta  Tetratic phases of rectangles using DFT  14:30 s.t.
Mi 31.05.2017   C. Scholz  There's something hidden in the basement - active matter driven by vibrations!  14:30 s.t.
Do 01.06.2017   E. Allahyarov  A review of new developments in responsive nanocomposites  14:30 s.t.
Mo 12.06.2017   S. Babel  DDFT of charged particles in an electric field  14:30 s.t.
Mi 14.06.2017   S. Jahanshahi  The Brazil nut and reverse Brazil nut effects  14:30 s.t.
Mi 28.06.2017   M. Puljiz  Two magnetically interacting rigid inclusions in a soft gel  13:30 s.t.
Mi 28.06.2017   U. Zimmermann  Dynamical Density Functional Theory in 2D Microchannels  14:30 s.t.
Fr 30.06.2017   A. Gabriëlse  Crystallization of nanoparticles with square-shoulder interactions  14:30 s.t.
gez.: Prof. Dr. H. Löwen

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Seminar über "Spezielle Probleme der Computersimulation weicher Materie"

Ort: HHU Düsseldorf, Seminarraum 25.32.O2.51
Programm:
DatumSprecher/inThemaZeit
Mi 03.05.2017   G. Pessot  Self-induced polar order for pushers and pullers  13:30 s.t.
Mo 29.05.2017   S. Ganguly  Interfacial free energies at solid-solid interfaces  14:30 s.t.
Mi 31.05.2017   C. Scholz  There's something hidden in the basement - active matter driven by vibrations!  14:30 s.t.
Do 01.06.2017   E. Allahyarov  A review of new developments in responsive nanocomposites  14:30 s.t.
Mo 12.06.2017   S. Babel  DDFT of charged particles in an electric field  14:30 s.t.
Mi 14.06.2017   S. Jahanshahi  The Brazil nut and reverse Brazil nut effects  14:30 s.t.
Fr 16.06.2017   M. Golkia  Residual stresses in glasses  14:30 s.t.
Fr 30.06.2017   A. Gabriëlse  Crystallization of nanoparticles with square-shoulder interactions  14:30 s.t.
Do 27.07.2017   M. Eshraghi  Calculation of interfacial free energy via Thermodynamic Integration (TI)  14:30 s.t.
gez.: Prof. Dr. J. Horbach

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Seminar “Soft Matter”

Ort: HHU Düsseldorf, Seminarraum 25.32.O2.51
Programm:
DatumSprecher/inInstitutZeit
Fr 28.07.2017   Suvendu Mandal  Universität Innsbruck, Austria  14:30 s.t.
Suvendu Mandal: „The dynamics of driven and active Brownian particles”
Universität Innsbruck, Austria - Seminar@HHUD: 28.7.17 14:30 s.t., Seminarroom 25.32 O2.51

While the linear response is well-characterized in terms of the fluctuation-dissipation theorem, few exact results are available for strong driving. Here we study the time-dependent velocity of a colloidal particle immersed in a dilute suspension of hard spheres in response to a step force switched on at time zero using Brownian dynamics simulations. Our main quantity of interest is the time-dependent mobility and its approach to the stationary state mobility. A stationary state solution for the mobility exact in first order of the packing fraction has been established earlier in terms of a power-series expansion with respect to the force on the tracer particle [1]. We extend this result to the case of arbitrarily strong driving including the complete time-dependence of the response upon switching on the force. We show that in the stationary state, our analytic solution recovers the anticipated limit for strong driving [1] and captures the response in first order of the packing fraction for any strength of the force.

We also investigate active colloidal hard-sphere glasses using Brownian dynamics simulations. While the properties of passive colloidal glasses are fairly understood over the years, not much is known for active colloidal glasses. In this talk we discuss the decoupling between active speed and rotational diffusion in colloidal glasses. These findings agree with theoretical predictions obtained by the mode-coupling theory of the glass transition.

References

  1. T. M. Squires and J. F. Brady, Physics of Fluids 17, 0731
The dynamics of driven and active Brownian particles
Mi 26.07.2017   Vladimir S. Filinov  Russian Academy of Sciences, Moscow, Russia  14:30 s.t.
t.b.a.
Di 27.06.2017   William van Megen  RMIT Melbourne, Australia  14:30 s.t.
William van Megen: „Collective modes in hard sphere systems; cage effect”
RMIT Melbourne, Australia - Seminar@HHUD: 27.6.17 14:30 s.t., Seminarroom 25.32 O2.51

It’s axiomatic that the slowing of diffusion, increasing sluggishness of flow and delay of the structural relaxation a fluid when its density is increased are due to the increasing congestion among the particles comprising the fluid. It is also generally accepted that these manifestations of dynamic slowing are due to the ”cage effect“ the microscopic picture in which particles are trapped, at least momentarily, by their respective neighbours. An attempt to examine the role of caging more closely considers the spread of the displacement distributions of Brownian particles. These distributions are necessarily biased by the presence of neighbouring particles. Accommodation of this bias by those neighbours conserves the displacement distribution locally and presents a collective mechanism for exploring configuration space that turns out to be more efficient than the intrinsic Brownian motion. Blocking of the bias effects caging of some particles, however locally in space and time. This incurs, through the impost of global conservation of probability (the average number of caged particles), a delayed, non-local collective process. Both collective mechanisms incur delay or stretching of time correlation functions, in particular the particle number and flux densities. This presentation identifies and distinguishes these mechanisms in existing data from dynamic light scattering experiments and computer simulations on systems of particles with hard sphere interactions.

Collective modes in hard sphere systems; cage effect
Fr 02.06.2017   Gerd Schröder-Turk  Murdoch University, Perth, Australia  14:30 s.t.
Mixtures of Pears and Oranges: From inverse micelles to labyrinth-like bicontinuous phases
Mi 17.05.2017   Rolf Schilling  Johannes-Gutenberg-Universität Mainz  14:30 s.t.
Extremely Confined Fluids: Thermodynamics and Dynamics
Do 04.05.2017   Christina Kurzthaler  Universität Innsbruck, Austria  14:30 s.t.
Christina Kurzthaler: „From self-propelled particles to semiflexible polymers”
Universität Innsbruck, Austria - Seminar@HHUD: 4.5.17 14:30 s.t., Seminarroom 25.32 O2.51

Self-propelled particles are intrinsically out of equilibrium and exhibit peculiar dynamical behavior. These active agents are subject to strong stochastic fluctuations, that compete with their persistent swimming motion. So far most studies consider the lowest order moments of the displacements only, while more general spatiotemporal information is encoded in the directly measurable intermediate scattering function, i.e. the Fourier transform of the probability density. In this talk, I will discuss analytic solutions of the intermediate scattering function of an active Brownian particle and a Brownian circle swimmer, and show, that our theoretical predictions agree very well with experimental observations of Janus particles. The mathematical analog to the self-propelled particle constitutes the semiflexible polymer. I will also provide an exact solution for the partition sum of a semiflexible polymer under compression and analyze its buckling behavior in terms of the force-extension relation.

From self-propelled particles to semiflexible polymers
Fr 21.04.2017   Céline Ruscher  Institut Charles Sadron, Strasbourg, France  14:30 s.t.
Voronoi glasses: a new model for probing glass transition
gez.: Prof. Dr. Egelhaaf, Prof. Dr. Horbach, Prof. Dr. Löwen

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poroSys-Vorträge

Datei: poroSys Talkslist

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Kolloquien

Ort: HHU Düsseldorf, Hörsaal 5J (Gebäude 25.31 Ebene 00)
Programm:
DatumSprecher/inInstitutZeit
Do 29.06.2017   Prof. Dr. Holger Stark  Institut für Theoretische Physik, Technische Universität Berlin  16:30 s.t.
Microswimmers: From design principles to their emergent collective behavior
Do 26.01.2017   Prof. Karsten Flensberg  Niels Bohr Institute, University of Copenhagen, Denmark  16:30 s.t.
Towards Majorana-based topological qubits?
Do 19.01.2017   Prof. Michael Eikerling  Simon Fraser University, Vancouver, Canada  16:30 s.t.
The Physics of Electrochemical Energy Conversion
Do 08.12.2016   PD Dr. Antonio Di Piazza  Max-Planck-Institut für Kernphysik, Heidelberg  16:30 s.t.
Tests of classical and quantum electrodynamics in intense laser beams
Do 24.11.2016   Prof. Dr. Susana Huelga  Universität Ulm  16:30 s.t.
Vibrations, Quanta and Biology
Do 27.10.2016   Prof. Joseph Indekeu  Theoretical Physics, KU Leuven, Belgium  16:30 s.t.
Short-range wetting in two dimensions: is it always second-order?
Für die Dozenten der Physik

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Seminar über Examensarbeiten aus dem Institut für Theoretische Physik, Lehrstuhl II

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Link: Physikalisches Kolloquium
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