Dynamic core hole screening in small-diameter conducting carbon nanotubes: A cluster density functional study

The many-electron response of a small-diameter conducting carbon nanotube, to the sudden creation of a 1score state, is studied using density functional theory with different Gaussian basis sets and the generalizedgradient approximation for exchange and correlation. Cluster computations are performed on carbonatoms located at a finite-size cylindrical network that is terminated by hydrogen atoms. Core-hole creationis simulated by replacing the 1s electron pair, localized at a central site of the structure, with effectivepseudo-potentials for both neutral and ionized atomic carbon. The same approach is used to describe a neutraland core-ionized C60 fullerene molecule. The overlaps between the excited states of the ionized systemsand the ground states of the neutral systems are combined in a Fermi's golden rule treatment yielding theshake-up spectra from the two clusters. The numerical response for the fullerene molecule is found ingood agreement with the measured X-ray photoelectron spectrum from thick C60 films, including the low energysatellites at excitation energies below 4 eV, within a peak position error of 0.3 eV. The nanotube spectrumreveals features in common with X-ray photoelectron data from Bucky balls and Bucky papers.