Charge density wave Madelung constant in a system of linear chains

Possibility of superconducting precursor effects in quasi-one-dimensional organic conductors : theory and experiments

“…In these calculations electron-phonon interaction may be included by an effective coupling constant and an energy cut off of the order of the phonon frequency. If the retardation of the electron-phonon interaction is fully accounted for, it has been shown [46,49] [53] and therefore leads to a Peierls transition at finite temperature [54,57]. On the other hand, coupling between superconducting order parameters requires electrons to move from one chain to the next, so that a BCS transition may only occur for finite interchain tunnelling integral [55,56,59].…”

A landau theory for the displacive phase transitions in TTF-TCNQ

“…The direct Coulomb energy between CDW's on TCNQ chains gives rise to a transverse correlation length of order [30] which is seen to be smaller than that due to the TTF-TCNQ tunnelling, and also too small to create transverse order. This supports our neglect of the direct Coulomb interaction between TCNQ chains in this work.…”

“…In order to account for this change, let us first consider Coulomb interactions between the chains [30,31]. Formally [32] [5] and J6rome [33] [ 11 ], or some infra-red measurements [34]), EF -2 000 K = 1/4 eV (from the plasma frequency [5], or the thermopower [35]), VQQ ~ 2-3 eV (assuming a molecular excitation energy of 2 eV, from molecular orbital calculations [17,18,19] or photoemission experiments [ 18]), this ratio is of order unity and the effect could be strong.…”

“…From the point of view of this work, the N-S bonds are in the a-direction, so they cannot account for what happens in the c-direction. Both the electron tunnelling [39] and Coulomb interactions [30] figure 7, but without the longitudinal displacement). Below 38 K, the extrema of pQ are at points of type g, i.e.…”

Dynamical Properties of Quasi-One-Dimensional Conductors: A Phase Hamiltonian Approach

“…The interchain coupling of the type of Equation (2.86) but without the spin degree of freedom, cf>i. has been employed in the discussion of the phase transition in the Peierls systems [53][54][55][56][57][58][59][60][61][62][63], where the quantum fluctuations can also be ignored due to the large effective mass (see Section 3). In this ca se the effective Hamiltonian is reduced to (2.88) where Jij only between the nearest neighbor chains, (i, j), is retained due to the strong z-dependence of Ko (z) once z ;::: 1.…”