Format

Send to

Choose Destination
Nat Commun. 2014 Jul 10;5:4351. doi: 10.1038/ncomms5351.

Scalar φ4 field theory for active-particle phase separation.

Author information

1
SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, UK.

Abstract

Recent theories predict phase separation among orientationally disordered active particles whose propulsion speed decreases rapidly enough with density. Coarse-grained models of this process show time-reversal symmetry (detailed balance) to be restored for uniform states, but broken by gradient terms; hence, detailed-balance violation is strongly coupled to interfacial phenomena. To explore the subtle generic physics resulting from such coupling, we here introduce 'Active Model B'. This is a scalar φ(4) field theory (or phase-field model) that minimally violates detailed balance via a leading-order square-gradient term. We find that this additional term has modest effects on coarsening dynamics, but alters the static phase diagram by creating a jump in (thermodynamic) pressure across flat interfaces. Both results are surprising, since interfacial phenomena are always strongly implicated in coarsening dynamics but are, in detailed-balance systems, irrelevant for phase equilibria.

PMID:
25008346
DOI:
10.1038/ncomms5351

Supplemental Content

Full text links

Icon for Nature Publishing Group
Loading ...
Support Center