Electron-beam-promoted fullerene dimerization in nanotubes: insights from DFT computations

Area of Science:

• * Computational chemistry
• * Materials science
• * Nanotechnology

Background:

• * Fullerenes are carbon molecules with unique properties.
• * Encapsulating fullerenes within carbon nanotubes (peapods) can alter their reactivity.
• * Understanding fullerene dimerization is key to designing novel carbon materials.

Purpose of the Study:

• * To investigate the mechanism and energy profile of fullerene dimerization within a peapod.
• * To compare the efficiency of radical cation versus neutral pathways for dimerization.
• * To elucidate the role of one-dimensional confinement provided by the peapod.

Main Methods:

• * Density Functional Theory (DFT) calculations to characterize stationary points and energy profiles.
• * Analysis of the reversible phase 1 of fullerene dimerization.
• * Car-Parrinello metadynamics simulations for the irreversible phase 2.

Main Results:

• * The radical cation mechanism exhibits significantly lower energy barriers than the neutral pathway.
• * One-dimensional confinement within the peapod enhances reaction efficiency.
• * Metadynamics simulations suggest structural reorganizations during the irreversible phase 2.

Conclusions:

• * Fullerene dimerization in peapods is favored by the radical cation mechanism.
• * Peapod confinement plays a crucial role in facilitating this reaction.
• * The study provides insights into the complex structural changes during fullerene coalescence.