  In order to investigate quantum and thermal phase transitions in the
Bechgaard salts and their sulfur analogs, we perform finite-temperature
Hartree-Fock calculations in one dimension with particular emphasis on the
interplay between charge ordering and lattice instability. The coexisting
charge- and spin-density-wave state as well as its precursor fluctuations in
(TMTSF)2PF6 and the lattice tetramerization in (TMTTF)2ReO4 are well
interpreted.
