Optical properties of spiroid C$_{300}$

Calculation results of the electronic spectrum of carbon nanospiroid C$_{300}$ are presented. The $\pi$-electron structure of the spiroid is calculated using the strong coupling method, in which the matrix element of the exchange interaction of neighboring electrons (the resonance integral) is considered as being dependent on the local curvature of the spiroid surface. The optical absorption coefficient is calculated in the framework of the Tautz model and the result is compared with experimental and astrophysical observational data. The calculated and experimental data are in good agreement.