Charge localization in organic conductors (TM)(2)X: The influence of anionordering

An investigation of the different contributions leading to charge localizat ion in a 1/2 or 1/4 filled band ID conductor has been conducted through a s tudy of transport properties in the solid solution [(TMTSF)(1-x) (TMTTF)(x) ](2)ReO4. The existence of an ordering transition of the anions allows to i dentify two contributions to the electronic potential with wave vector 4k(F ). ii dominant on-site 4k(F) potential besides the bond contribution is rev ealed when Umklapp scattering is pertinent via the weakening of the localiz ation arising at the (0, 1/2, 1/2) anion ordering which is stabilized under pressure in the compound [(TMTSF)(0.5) (TMTTF)(0.5)](2)ReO4 at variance wi th the enhancement of localization observed in the homomolecular (TMTTF)(2) ReO4 material.