2006 年 48 巻 1 号 p. 59-64
High resolution X-ray structure analyses revealed the condition for the charge ordering (CO) observed in the quasi one-dimensional compounds (TMTTF) 2X. The size and orientational ordering of the counter anion X control the dimerization and tetramerization of TMTTF molecules. The molecular dimerization suppresses the 4kF CO, while the tetramerization assists the 2kF CO. The phase diagram of the electronic states including 2kF and 4kF CO has been proposed associated with magnitudes of the molecular dimerization and tetramerization.