Nonequilibrium energy gaps in carbon nanotubes: Role of phonon symmetries

We report on a theoretical study of inelastic backscattering processes and quantum transport in metallic carbon nanotubes. The consequences of a Peierls-like mechanism due to e-ph interaction with optic phonons in the transport properties is explored. The occurrence of nonequilibrium energy gaps driven by an applied bias voltage is derived from a nonperturbative treatment of electron-phonon coupling with longitudinal optic as well as K A(1)' modes. The case of armchair tubes is explicitly considered, and further generalizations to tubes of arbitrary helicity are outlined.