Model system used to illustrate phase transition of a mixture of active and passive particles
Systems containing self-propelling particles, such as bacteria or artificial colloidal particles, are always out of equilibrium but may show interesting transitions between different states, reminiscent of phase transitions in Systems containing self-propelling particles, such as bacteria or artificial colloidal particles, are always out of equilibrium but may show interesting transitions between different states, reminiscent of phase transitions in equilibrium.
Snapshots from a molecular dynamics simulation with 547 colloids and 1,781 polymers in an elongated simulation box. The upper image shows an equilibrium configuration of the passive system which did not phase-separate. The lower image is the corresponding active system in its steady state which is clearly phase-separated. In both pictures, colloids are shown in yellow and polymers in black. (ill./©: Peter Virnau, JGU)
However, application of analytical and computational methodologies from equilibrium statistical mechanics is questionable to study properties of such active systems. An international team of researchers – including Dr. Peter Virnau and Professor Kurt Binder of Johannes Gutenberg University Mainz (JGU), Benjamin Trefz of the JGU Graduate School of Excellence "Materials Science in Mainz" (MAINZ), and scientists from India and the U.S. – has studied the phase separation of a mixture of active and passive particles via molecular dynamics simulations and integral equation theoretical calculations. The distinctive feature of the model used is that the "activity" of the particles is tunable, containing passive particles as a limiting case for which already phase separation occurs.
"Our research results demonstrate that the introduction of activity may not only hamper phase separation as shown previously, but can enhance it as well, based on the coordination among the active particles," explained Dr. Peter Virnau of the Institute of Physics at Mainz University. Moreover, the researchers provided an approximate mapping of the phase behavior and structural properties of this nonequilibrium problem onto an equilibrium problem. A general validity of this mapping is subject to further careful testing. The confirmation of such validity would be an important step forward in understanding properties of active matter.
Subir K. Das et al.
Phase Behavior of Active Swimmers in Depletants: Molecular Dynamics and Integral Equation Theory
Physical Review Letters, 15 May 2014
Dr. Peter Virnau
Condensed Matter Theory Group (KOMET)
Institute of Physics
Johannes Gutenberg University Mainz (JGU)
D 55099 Mainz, GERMANY
phone +49 6131 39-20493
fax +49 6131 39-20496
Petra Giegerich | idw - Informationsdienst Wissenschaft
Streamlining accelerated computing for industry
24.08.2016 | DOE/Oak Ridge National Laboratory
Lehigh engineer discovers a high-speed nano-avalanche
24.08.2016 | Lehigh University
Scientists and engineers striving to create the next machine-age marvel--whether it be a more aerodynamic rocket, a faster race car, or a higher-efficiency jet...
Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.
In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...
Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.
Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...
Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...
A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.
25.08.2016 | Event News
24.08.2016 | Event News
12.08.2016 | Event News
29.08.2016 | Materials Sciences
29.08.2016 | Life Sciences
29.08.2016 | Medical Engineering