The two-chain problem: A model of TTF-TCNQ
The two-chain, inverted band model for TTF-TCNQ is solved by the exact methods developed by Luther and Emery and by Chui and Lee. On each chain, there are intrachain interactions g1 and g2, and there are interchain interactions w1 and w2. We investigate all of the possible two-particle correlation functions, of which the new divergent ones not present in the single chain problem are of the excitonic insulator type. In addition, we investigate essentially all of the many possible four-particle correlation functions. For the single chain, there are two divergent ones; the 4kF response found by Emery, and a four-particle condensation of two Cooper pairs. For the two-chain problem, there are many others, the most unusual of which are of the excitonic molecule type. In addition, the 4kF response is enhanced by the interchain coupling, and is divergent for weak intrachain coupling as well as for strong coupling. Using renormalization group techniques, we find that the essential features of the temperature dependence of the relative size of the 4kF and 2kF excitations recently observed can be explained in terms of a crossover from a region in which the 4kF excitation is dominant to one in which the 2kF charge density wave response is dominant.
KeywordsResponse Function Cooper Pair Single Chain Interchain Interaction Jersey 07974
Unable to display preview. Download preview PDF.
- 1.J. P. Pouget, S. K. Khanna, F. Denoyer, R. Comès, A. F. Garito, and A. J. Heege Phys. Rev. Lett. 37, 437 (1976).Google Scholar
- 2.D. C. Mattis and E. H. Lieb, J. Math. Phys. 6, 304 (1965).Google Scholar
- 3.A. Luther and V. J. Emery, Phys. Rev. Lett. 33, 589 (1974).Google Scholar
- 4.S.-T. Chui and P. A. Lee, Phys. Rev. Lett. 35 315 (1975).Google Scholar
- 5.H. Gutfreund and R. A. Klemm, Phys. Rev. B 14, 1073 (1976).Google Scholar
- 6.N. Menyhárd and J. Sólyom, J. Low Temp. Phys. 12, 529 (1973); J. Sólyom, ibid. 12, 547 (1973).Google Scholar
- 7.H. Fukuyama, T. M. Rice, C. M. Varma, and B. I. Halperin, Phys. Rev. B 10, 3775 (1974).Google Scholar
- 8.V. J. Emery, Phys. Rev. Lett. 37, 107 (1976).Google Scholar
- 9.L. Mihály and J. Sólyom, J. Low Temp. Phys. 24 579 (1976).Google Scholar
- 10.P. A. Lee, T. M. Rice, and R. A. Klemm, unpublished.Google Scholar