The Ginzburg-Landau expansion in the simple model of a superconductor witha pseudogap

We propose a simple model of the electron spectrum of a two-dimensional sys tem with hot sections on the Fermi surface that significantly transforms th e spectral density (pseudogap) in these sections. Using this model, we set up a Ginzburg-Landau expansion for s and d type Cooper pairing and analyze the effect of the pseudogap in the electron spectrum on the main properties of a superconductor. (C) 1999 American Institute of Physics. [S1063-7761(9 9)01802-8].