Journal article

Effective equilibrium states in the colored-noise model for active matter I. Pairwise forces in the Fox and unified colored noise approximations

  • Wittmann, René Department of Physics, University of Fribourg, Switzerland
  • Maggi, C. NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter, Laboratory, Roma, Italy
  • Sharma, Abhinav Department of Physics, University of Fribourg, Switzerland - Leibniz-Institut für Polymerforschung Dresden, Germany
  • Scacchi, Alberto Department of Physics, University of Fribourg, Switzerland
  • Brader, Joseph M. Department of Physics, University of Fribourg, Switzerland
  • Marini Bettolo Marconi, Umberto Scuola di Scienze e Tecnologie, Universit? di Camerino, Camerino, INFN Perugia, Italy
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  • Journal of Statistical Mechanics: Theory and Experiment. - 2017, vol. 2017, no. 11, p. 113207
English The equations of motion of active systems can be modeled in terms of Ornstein– Uhlenbeck processes (OUPs) with appropriate correlators. For further theoretical studies, these should be approximated to yield a Markovian picture for the dynamics and a simplified steady-state condition. We perform a comparative study of the unified colored noise approximation (UCNA) and the approximation scheme by Fox recently employed within this context. We review the approximations necessary to define effective interaction potentials in the low-density limit and study the conditions for which these represent the behavior observed in two-body simulations for the OUPs model and active Brownian particles. The demonstrated limitations of the theory for potentials with a negative slope or curvature can be qualitatively corrected by a new empirical modification. In general, we find that in the presence of translational white noise the Fox approach is more accurate. Finally, we examine an alternative way to define a force-balance condition in the limit of small activity.
Faculté des sciences et de médecine
Département de Physique
  • English
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