title: Fick's law, green-kubo formula, and Heisenberg's equation of motion
abstract: Fick's law is important in transport theory and nonequilibrium statistical mechanics. The Heisenberg equation of motion for density is examined to see how it could be reduced to the diffusion equation, which is exactly equivalent to Fick's law. Conditions that are required have been noted and their implications explored.
authors.affiliation: Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602-2451 and Korea Institute for Advanced Study, Seoul 130-012, Korea.
authors.initials: MH
authors.lastname: Lee