## Abstract

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 ≥ μk_{B}T, with k_{B} 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 language | English |
---|---|

Pages (from-to) | 2497-2508 |

Number of pages | 12 |

Journal | Journal of the Physical Society of Japan |

Volume | 72 |

Issue number | 10 |

DOIs | |

Publication status | Published - 2003 Oct 1 |

## Keywords

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

## ASJC Scopus subject areas

- Physics and Astronomy(all)