Response to external GHz and THz radiation of K⁺@C₆₀ endohedral complex in cavity of carbon nanotube containing polymerized fullerenes

We investigate how the electrical conductivity of a functionalized nanotube affects its absorption of THz radiation. The nanotube is a periodic structure made from C₆₀ fullerenes that are regularly polymerized with each other and with a nanotube wall with a step of several nanometers. A K⁺@C₆₀ complex, where K⁺ is a positive potassium ion, oscillates freely in the THz range in a potential well in the nanospace between polymerized fullerenes. Increasing the vibration amplitude of the K⁺@C₆₀ complex at the resonance frequency redistributes the electron density on the tube and creates a partial flow of charge to the fullerene frame of the complex, which changes the conductivity of the nanotube by several percent, depending on the applied voltage. This phenomenon can form the basis of a nanodevice for detecting THz radiation.