Motivated by recent experimental results of hydrocarbon formation in small diameter carbon nanotubes filled with ferrocene molecules, we performed molecular dynamics simulations with a DFT-adjusted tight-binding method. We increased the number of carbon atoms from 60 to 150 by inserting carbon pentagon rings into a (14,0) nanotube. We found [ 1] that the structures formed during the simulation depend on the temperature as well as on the density of the carbon atoms. At lower temperatures, we obtained graphene ribbons and at higher temperatures fullerenes or nanotubes were formed. For large enough density of the carbon atoms, the formation of nanotube like structure was preferred at both low and high temperatures.
 István László, Bálint Gyimesi, János Koltai and Jenő Kürti, Physica Status Solidi B 2017, 1700206, DOI: 10.1002/pssb.201700206