The number-density–heat-density correlation function ${\chi }_{\mathrm{nQ}}$(q;ω) for a noninteracting disordered electronic system, is evaluated at small wave vector and frequency by diagrammatic techniques and shown to meet its general hydrodynamic requirements. This analysis leads us to the conclusion that the ratio of the coefficient Q of thermoelectric power and of the temperature T diverges at the localization transition.

• Received 2 November 1987

DOI:https://doi.org/10.1103/PhysRevB.37.6663