Quantum and thermal phase transitions in the Bechgaard salts and their analogs

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.