Abstract :
Summary form only given. The two main sources of information on the one-dimensional electronic properties of the Bechgaard salts are: i) experimental results (resistivity, susceptibility,...) interpreted within the context of g-ology; ii) quantum chemistry calculations based on X-Ray and neutron scattering measurements. These approaches yield apparently conflicting results concerning the magnitude of the dimerization in the TMTSF series, and the relative magnitude of the Coulomb repulsion between TMTTF and TMTSF. To resolve this, we propose to study various extensions of the 1D Hubbard model, which should allow one to make contact with both quantum chemistry and g-ology. Using recent analytical and numerical techniques, we have calculated: i) the critical exponents of the quarter-filled U - V model as a function of U and V; ii) the charge gap /spl Delta//sub p/ of the dimerized Hubbard model as a function of U/t/sub 1/ and t/sub 2/t/sub 1/. A study of the susceptibility is in progress. A detailed account of the implications of these results for the Bechgaard salts will be given.
