title: Applicability of the Taylor-Green-Kubo formula in particle diffusion theory.
abstract: Diffusion coefficients of particles can be defined as time integrals over velocity correlation functions, or as mean square displacements divided by time. In the present paper it is demonstrated that these two definitions are not equivalent. An exact relation between mean square displacements and velocity correlations is derived. As an example of the applicability of these results so-called drift coefficients of energetic particles are discussed. It is explained why different previous approaches in drift theory provided contradicting results.
authors: Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada. andreasm4@yahoo.com
authors: A
authors: A
authors: Shalchi