Pullout Force and Inlet Oscillation in Telescopic Carbon Nanotubes: A Quantum Study

The noncovalent interaction energy as a function of the coreextension in double-walled carbon nanotubes (DWCNT) was accuratelycalculated in the frame of density functional theory, considering dispersioncorrection and without resorting to adjustable parameters. A linear correlationbetween the change of the noncovalent energy and core displacement wasestablished for the first time through a pure quantum mechanics approach; hence,the force needed to pull out the DWCNT core was accurately calculated. Thisforce was found to be in good agreement with experimental values reported in theliterature. Furthermore, the effect of the DWCNT edges was considered in thecalculation of the potential energy profile, and the frequency, associated with theoscillation of core inlet, was calculated for the first time through a quantumapproach. This frequency falls in the low infrared region, and it depends on thechemical nature of the oscillator edges. The work highlights that the noncovalentH···? interaction controls the inner shell oscillation and it should be considered, beyond the stacking between inner and outer walls,as a driving force for the activation of the telescopic process. As a result, this noncovalent interaction can be tuned for the design ofnano-dynamometers with well-defined force constants.