title: Chirality dependence of quantum thermal transport in carbon nanotubes at low temperatures: a first-principles study.
abstract: We study the transport properties of single-walled carbon nanotubes (SWCNTs) using the nonequilibrium Green's function method based on first-principles calculations. We compared three SWCNTs with different chiralities (3, 3), (5, 0), and (4, 2), and found that the thermal conductance varies significantly with the chirality, especially at low temperatures. Such differences are attributed to the dependence on the chirality of the frequency of the lowest optical mode and phonon-phonon interaction with the semi-infinite leads. To obtain accurate low-vibrational frequencies, a force constant correction based on the Lagrange undetermined multiplier method was employed. The phonon-phonon interaction was analyzed in terms of the projection of the phonon coupling with the semi-infinite leads onto the normal modes of the center region. Our result indicates that high optical mode frequency and weak phonon coupling on the armchair (3, 3) SWCNT are the origin of the long quantized plateau found in the experimental thermal conductance.
authors.affiliation: Department of Chemical System Engineering, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan. hata@tcl.t.u-tokyo.ac.jp
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Hata
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kawai
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Ohto
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamashita