Time-Domain Ab Initio Studies of Excitation Dynamics in Carbon Nanotubes

We have developed state-of-the-art non-adiabatic molecular dynamics techniques and implemented them within time-dependent density functional theory in order to model the ultrafast excitation processes in CNTs at the atomistic level and in real time. Our ab initio studies of CNTs directly mimic the experimental data and reveal many intriguing features of the excitation dynamics, including non-radiative fluorescence quenching, fast intrinsic intraband relaxation, phonon-induced component of fluorescence linewidths, the importance of defects, the dependence of the relaxation rate on the excitation energy and intensity, and a detailed understanding of the role of active phonon modes. \textbf{1}. C. F. Craig, W. R. Duncan, O. V. Prezhdo ``Trajectory surface hopping in the time-dependent Kohn-Sham theory for electron-nuclear dynamics'', \textit{Phys. Rev. Lett}.,\textbf{ 95} 163001 (2005) \textbf{2}. B. F. Habenicht, C. F. Craig, O. V. Prezhdo, ``Electron and hole relaxation dynamics in a semiconducting carbon nanotube'', \textit{Phys. Rev. Lett.} \textbf{96} 187401 (2006) \textbf{3}. B. F. Habenicht, H. Kamisaka, K. Yamashita and O. V. Prezhdo, ``Ultrafast vibrationally-induced dephasing of electronic excitations in semiconducting carbon nanotubes, \textit{Nano Lett.,} submitted \textbf{4}. B. F. Habenicht, C. F. Craig, O. V. Prezhdo, ``Quenching of fluorescence in a semiconducting carbon nanotube: time-domain ab initio study'', \textit{Phys. Rev. Lett.}, submitted.