One-dimensional electronic properties of the Bechgaard salts

An estimate of the gap Δρ that opens at the Fermi level in a 3/4-filled Hubbard model with alternating hopping integrals is obtained on the basis of weak and strong coupling results. Assuming that this gap will induce a minimum of resistivity at a temperature Tρ ≅ Δρ/π, we show that the hopping integrals provided by quantum chemistry calculations based on structural data are in reasonable agreement with the experimental resistivity curves if U is the same for all compounds (≅ 850meV). In particular, very small values can be obtained for the TMTSF series without assuming that the dimerization is itself very small. The discrepancies between this model and the magnetic data are briefly discussed. (orig.)