ELECTRON-PHONON COUPLING IN LOW-DIMENSIONAL ORGANIC SUPERCONDUCTORS

The relative importance of the coupling of electrons with intra- and i nter-molecular phonons in setting up the organic superconductivity is addressed. We base our considerations on a firmly established set of e lectron molecular vibration coupling constants for the TMTTF molecule. By the use of three different models of the BCS, strong coupling and non adiabatic type we find that, in order to attain critical temperatu res (T(c)) in the typical range of 1 to 10 K, large values for the ele ctron inter-molecular phonon coupling constants are needed. We also re port a theoretical analysis of the effects of isotopic substitution of the carbon atoms in a TTF based molecule. Through a simple model of t wo coupled oscillators and by the use of the experimental data availab le for TMTTF, we estimate isotopic T(c) shifts which may be useful for qualitative comparison with experimental data.