Diffusion coefficients for two-state Brownian motors

Kazuo Sasaki

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Based on the Fokker-Planck equation, a formula for the effective diffusion coefficient D is derived for a Brownian particle undergoing one-dimensional motion in a two-state Brownian motor (ratchet) in which a spatially periodic, asymmetric potential acting on the particle switches between two states stochastically. It turns out that D is in close relation to the "mobility" μ defined as dυ/dF where υ is the average velocity of the particle and F is the external force acting on it. The formula is applied to specific examples, and it is found that inequality D ≥ μkBT, with kB the Boltzmann constant and T the temperature, holds in all the cases investigated. In the light of new results obtained here, an earlier analysis of a biological molecular motor KIF1A based on the "on-off" ratchet is re-examined.

Original languageEnglish
Pages (from-to)2497-2508
Number of pages12
JournalJournal of the Physical Society of Japan
Issue number10
Publication statusPublished - 2003 Oct 1


  • Brownian motor
  • Diffusion coefficient
  • Fokker-Planck equation
  • Mobility
  • Ratchet

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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