Thermodynamic characteristics of the one-dimensional attractive Hubbard model are calculated by means of the generalized self-consistent field (GSCF) approach for a wide range of interaction strength U less than or equal to, 0, in the presence of external magnetic field h greater than or equal to 0, temperature T greater than or equal to 0 and electron concentration 0 less than or equal to n less than or equal to 1. The GSCF theory shows a sharp transition driven by h > 0 and T from the uniform superconducting state into a spatially inhomogeneous state in which the order parameter Delta ((-))(q) has wave vector (0 < \q \ less than or equal to pi). The concentration of double occupied sites and the bound electron pairs with opposite spins n(pair) are calculated and we found a simple relationship between the order parameters Delta ((-))(q) and average spin s, valid for the arbitrary U, all n and h. (C) 2001 Published by Elsevier Science B.V.
