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
A blueprint for clearing the skies of space debris
17.04.2015 | RIKEN
Quantum Physics – Hot and Cold at the Same Time
17.04.2015 | Ruprecht-Karls-Universität Heidelberg
Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a supermassive black hole in a distant galaxy
Astronomers from Chalmers University of Technology have used the giant telescope Alma to reveal an extremely powerful magnetic field very close to a...
A team of physicists from MPQ, Caltech, and ICFO proposes the combination of nano-photonics with ultracold atoms for simulating quantum many-body systems and creating new states of matter.
Ultracold atoms in the so-called optical lattices, that are generated by crosswise superposition of laser beams, have been proven to be one of the most...
According to new research out of the Texas A&M Health Science Center College of Medicine, that is indeed the case. Chetan Jinadatha, M.D., M.P.H., assistant...
Researchers from ICFO, MIT and UC Riverside have been able to develop a graphene-based photodetector capable of converting absorbed light into an electrical voltage at ultrafast timescales
The efficient conversion of light into electricity plays a crucial role in many technologies, ranging from cameras to solar cells.
Electrical charges not only move through wires, they also travel along lengths of DNA, the molecule of life. The property is known as charge transport.
In a new study appearing in the journal Nature Chemistry, authors, Limin Xiang, Julio Palma, Christopher Bruot and others at Arizona State University's...
13.04.2015 | Event News
25.03.2015 | Event News
19.03.2015 | Event News
17.04.2015 | Power and Electrical Engineering
17.04.2015 | Earth Sciences
17.04.2015 | Physics and Astronomy