  We investigate the stable structures of Fe-filled single-walled carbon
nanotubes (SWNTs) on Ni(111), using density functional theory calculations. We
find stable geometries and electronic states for the nanotube on Ni(111). We
propose the possibility that the C-C bonds of carbon nanotube are broken by Fe
wire and Ni surface. That is, when Fe-filled SWNT(3, 3) adsorb on Ni(111)
surface, SWNT transforms into arch-like structure.
