Theoretical investigation of photoabsorption in Cyanogen cluster

In this paper, photoabsorption spectrum of Cyanogen cluster has been investigated. The calculations of excitation energies, oscillator strengths and transition dipole moments are performed using the time-dependent density functional theory (TDDFT) approach. The first resonant peak for NCCN and NCNC isomer are found to occur at around 7.66, 6.94 eV, respectively. Furthermore, in case of NCCN, NCNC isomer the spectacular transitions of the spectra occurred in the far-UV (FUV) region of the electromagnetic spectrum. In addition, the absorption spectrum of NCNC isomer is red-shifted as compared to that of NCCN isomer. The natures of these excitations were investigated by analyzing the frontier molecular orbital´s involved with these optical transitions. That means the LUMO of NCCN is combinations of s (85%) and p (15%) hybrid orbital´s whereas in case of the NCNC, the LUMO corresponding to the first peak is contributed by both s (65%) and p (35%) orbits. However, the HOMO of both NCCN and CNCN are purely s-types.