DIFFUSION AND CORRELATION IN A COHERENT REPRESENTATION

Using a Fock-space formalism for the Master equation and introducing t he density operator we present an unified method to derive kinetic equ ations for hopping processes with and without exclusion on a lattice, The corresponding Liouvillians are written in terms of Fermi or Bose o perators, respectively. Although the Liouvillians are different the av eraged particle numbers obey the same diffusion equation. Differences appear in the correlation functions only. The Master equation can be t ransformed into a differential equation in a coherent state representa tion. Using the algebraic properties of Grassmann numbers we are able to find the exact stationary solution for diffusion with exclusion. Th e conductivity can be derived in the bosonic and the fermionic case. T he results are in accordance with those obtained with different other methods.