Stephan De Bièvre (Univ. Lille)

Diffusion, linear friction and Ohmic transport in a Hamiltonian open system.
  
Joint work with P. Lafitte, P. Parris and A. Silvius.

I will report on analytical and numerical work on a Hamiltonian model of a particle moving through a one-dimensional periodic medium with which it exchanges momentum and energy. The medium is modeled with local harmonic degrees of freedom and can be thought of as either a periodic inelastic Lorentz gas or as a classical version of the Holstein polaron model. At positive temperatures the particle executes a diffusive motion in absence of a driving field and exhibits Ohmic behaviour when such a field is present. We exhibit an adiabatic-nonadiabatic transition as a function of the temperature in the behaviour of the system, with two different power law dependences of the diffusion constant at high and low temperatures. I will discuss the validity of the Kubo relation in this context.