ELECTRON-TRANSPORT AT THE ANDERSON TRANSITION

The low-temperature behavior of transport properties across an Anderso n-type metal-insulator transition is considered. It is shown that prev ious discussions are flawed; in particular, we demonstrate that the th ermopower S is not divergent as the mobility edge E(c) is approached f rom the metallic side. At E(c), S achieves a temperature-independent v alue, determined solely by the conductivity index nu. Furthermore, far from being universal in the metallic phase, the Lorentz number change s as the mobility edge is approached and, in addition, depends on nu. We also prove that, contrary to previous assertions, the thermal condu ctivity varies like T(v+1) as T-->0.