Eur. Phys. J. B 80, 355-362 (2011)
https://doi.org/10.1140/epjb/e2011-10952-1

Tubular fullerenes inside carbon nanotubes: optimal molecular orientation versus tube radius

¹ Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
² Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, Pervomayskaya 91, 620990 Ekaterinburg, Russia

Corresponding author: ^a bart.verberck@ua.ac.be

Received: 5 December 2010
Revised: 2 February 2011
Published online: 16 March 2011

Abstract

We present an investigation of the orientations and positions of tubular fullerene molecules (C₉₀, ..., C₂₀₀) encapsulated in single-walled carbon nanotubes (SWCNT), a series of so-called fullerene nanopeapods. We find that increasing the tube radius leads to the following succession of energetically stable regimes: (1) lying molecules positioned on the tube's long axis; (2) tilted molecules on the tube's long axis; and (3) lying molecules shifted away from the tube's long axis. As opposed to C₇₀ and C₈₀ molecules encapsulated in a SWCNT, standing orientations do not develop. Our results are relevant for the possible application of molecular-orientation-dependent electronic properties of fullerene nanopeapods, and also for the interpretation of future experiments on double-walled carbon nanotube formation by annealing fullerene peapod systems.