Coulomb interaction in disordered metals and HTSC

We consider underdoped or overdoped cuprates as disordered conductors. The diffusion coefficient D can be as low as 10(-1) m(2) s(-1). Under these con ditions Coulomb interaction between electrons must be taken into account. T he main effect is to open a dip in the density of state near the Fermi leve l. We show that this model explains most of the observed features of the so -called "pseudogap" in the normal state including its value, anisotropy and variation with doping. Such a model applied to disordered metals explains the dips observed in conductance measurements. (C) 2001 Elsevier Science B. V. All rights reserved.