  The apex region of a capped (5,5) carbon nanotube (CNT) has been modelled
with the DFT package ONETEP, using boundary conditions provided by a classical
calculation with a conducting surface in place of the CNT. Results from the DFT
solution include the Fermi level and the physical distribution and energies of
individual Kohn-Sham orbitals for the CNT tip. Application of an external
electric field changes the orbital number of the highest occupied molecular
orbital (the HOMO) and consequently changes the distribution of the HOMO on the
CNT.
