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Scalar phi^4 field theory for active-particle phase separation

Wittkowski, Raphael; Tiribocchi, Adriano; Stenhammar, Joakim LU ; Allen, Rosalind; Marenduzzo, Davide and Cates, Michael (2014) In Nature Communications 5(Published online 10 July 2014).
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 φ4 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... (More)
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 φ4 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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Nature Communications
volume
5
issue
Published online 10 July 2014
publisher
Nature Publishing Group
external identifiers
  • wos:000340615500042
  • scopus:84904327902
ISSN
2041-1723
DOI
10.1038/ncomms5351
language
English
LU publication?
yes
id
6a8f62dc-5d10-4d74-b83d-7dfa8cd25249 (old id 4580824)
alternative location
http://www.nature.com/ncomms/2014/140710/ncomms5351/full/ncomms5351.html
date added to LUP
2014-09-22 12:42:11
date last changed
2017-11-19 03:57:06
@article{6a8f62dc-5d10-4d74-b83d-7dfa8cd25249,
  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 φ4 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.},
  articleno    = {4351},
  author       = {Wittkowski, Raphael and Tiribocchi, Adriano and Stenhammar, Joakim and Allen, Rosalind and Marenduzzo, Davide and Cates, Michael},
  issn         = {2041-1723},
  language     = {eng},
  number       = {Published online 10 July 2014},
  publisher    = {Nature Publishing Group},
  series       = {Nature Communications},
  title        = {Scalar phi^4 field theory for active-particle phase separation},
  url          = {http://dx.doi.org/10.1038/ncomms5351},
  volume       = {5},
  year         = {2014},
}