Lattice dynamics and electron-phonon interaction in carbon nanotube

ĽK.-P. Bohnen1, R. Heid1, H.J. Liu2 und C.T. Chan2
1Institut für Festkörperphysik, Forschungszentrum Karlsruhe, P.O.B. 3640, D-76021 Karlsruhe, Germany
2Dept. of Physics, University of Science and Technology, Clear Water Bay, Kowloon, Hongkong, China

Over the past decade the interest in understanding the physical properties of carbon nanotubes has grown enormously. This is based not only on their potential for applications but also due to their role as model systems for studying properties in one dimension. Especially the electron-phonon interaction is of interest with respect to Peierls transition [1], Kohn anomalies and superconductivity [2]. Using density functional perturbation theory we have calculated the complete phonon dispersion for (3,3) and (5,0) tubes. Both tubes show instabilities at q=2kF which can be seen in certain phonon modes. Due to the special topology of the Fermi surface for (n,n) tubes we find also phonon anomalies at q=0 for the (3,3) tube. Part of these have already been seen in other studies [3]. Since the instabilities at q=2kF show up usually at q vectors incommensurable with the lattice periodicity it is exceptionally difficult to see these effects in frozen-phonon calculations. We will present comparison with Raman measurements and approximate theoretical treatments [4].

[1] M. Th. Figge et al., Phys. Rev. Lett 86, 4572 (2001)

[2] Z. K. Tang et al., Science 292, 2462 (2001)

[3] O. Dubay et al., Phys. Rev. B 67, 035401 (2003)

[4] R. Barnett at al., cond-mat/0305006v2 (2003)