Extended Data Fig. 1: DFT results of (TMTTF)2X with different anions X = SbF6, PF6, AsF6 and BF4.

a, Band structure. Eintra: the bandwidth of the metallic band; Einter: the distance from Fermi energy EF to the band maximum of bands below -2 eV; Δℏω: the width of the hyper-gap. b, The dependence of Eintra, Einter, Δℏω, and the effective mass m* (me is the free electron mass) on different anions.