Influence of 5-atom rings on the optical properties of amorphous carbon nitride

The optical properties of three amorphous tetrahedral carbon-based clusters of the type α-C17-iNiH24 with 5-atom rings have been calculated. The hydrogens are used to passivate the outermost dangling bonds and t is 0, 1 or 4. The theoretical DFT-LDA based method used minimizes the energy of the clusters and provides the energy spectrum and the optical transitions for the minimum energy structures. The optical absorption spectrum of each cluster is analyzed and a comparison is made with previously reported spectra for clusters with 6-atom boat-type rings in order to see the influence of the present atomic topology.