We discuss the relationship between the two possible descriptions of t
he one-dimensional electronic properties of the Bechgaard salts, namel
y: i) microscopic models, like the extended Hubbard model, directly re
lated to quantum chemistry, and ii) effective low-energy models, like
g-ology, used to interpret low-temperature experiments. We show that i
t is now possible to calculate several low-energy properties of one-di
mensional microscopic models, like the critical exponents, the charge
gap and the Pauli susceptibility, and that this leads to a new interpr
etation of low-temperature experimental data and resolves some of the
contradictions in the field.