Concerning on your suspected about that, “why I persist in using (TD-LSDA) for calculating the optical properties of pristine and functionalized adamantane molecules?” which had shown in previous report. My reason used (TD-LSDA) approximation because considering only the electronic results, when comparison is the nearest with the experimental result but incorrect for predicting the optical properties. From learn more about difference of exchange-correlation terms, it found that local spin density (LSDA) and generalized gradient approximations (GGA) cannot describe bound excitonic states due to lack of an effective attractive Coulomb interaction between photo-excited electrons and holes, which are not accurate enough for describing quasi-particles (such as excitons, phonons etc.) .In contrast, the hybrid density functional, include long-rang non-local and non-adiabatic corrections in from of a fraction of the exact exchange (Hartree-Fock), are able to reproduce the excitonic effects.