Electronic structure and optical absorption of C$_{90}$ fullerene isomers

The energy spectra and optical absorption spectra of isomers Nos. 1, 6, 16 and 46 of fullerene C$_{90}$ are calculated. Due to the comparison of theoretical and experimental optical absorption spectra, three previously synthesized isomers of C$_{90}$ fullerene have been identified. The calculations are carried out within the framework of the developed approach, taking into account the intra-node Coulomb interaction of $\pi$-electrons, which plays a crucial role in the formation of the electronic and optical properties of fullerenes.