We give a full renormalization-group treatment of the electron density-density correlation function in a disordered system near the mobility edge. We extract the scaling behavior of the diffusion constant and conductivity in the critical region. Thus, the behavior of these quantities as a function of wave number and frequency is determined and the crossover between the high-frequency and large-wave-number domains is given explicitly.

• Received 16 August 1985

DOI:https://doi.org/10.1103/PhysRevB.33.683