  Combining time-dependent density functional calculations for electrons with
molecular dynamics simulations for ions, we investigate the dynamics of excited
carriers in a (3,3) carbon nanotube at different temperatures. Following an
hv=6.8 eV photoexcitation, the carrier decay is initially dominated by
efficient electron-electron scattering. At room temperature, the excitation gap
is reduced to nearly half its initial value after ~230 fs, where coupling to
phonons starts dominating the decay. We show that the onset point and damping
rate in the phonon regime change with initial ion velocities, a manifestation
of temperature dependent electron-phonon coupling.
