Pocket and antipocket conformations for the CH₄@C₈₄ endohedral fullerene

Abstract

Abstract The endohedral fullerene CH 4 @C 84 has been studied using density functional theory (DFT) and second‐order Møller–Plesset perturbation theory (MP2). In addition to the structure with a CH bond of CH 4 in a tetrahedral pocket conformation, we find an alternative minimum, very close in energy (6.3–9.5 kJ/mol higher according to the level of theory), with the methane inverted, which we call the antipocket conformation. Computed IR spectra are reported for CH 4 @C 84 and also for the reference system CH 4 @C 60 . The calculated vibrational levels, in a harmonic approximation, reveal close‐lying translational, librational, and shell‐vibrational modes. The results are also presented for the isoelectronic species NH @C 60 . © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007