INVESTIGATION OF EXCITATION AND EMISSION PROPERTIES OF FLUORESCENCE COMPOUNDS BY DFT AND TD-DFT METHODS

Abstract

The density functional theory and time-dependent density functional theory methods were used for the investigation of the excitation and emission properties of some fluorophores. The calculations were based on the optimized geometries of ground states and excited states at the B3LYP functional and LanL2DZ basis set. The results clarified the nature of the optical properties of the compounds and agreed well with experimental data. The calculated values of excitation energies and emission energies of the compounds were higher than the experimental values. These large errors occurred when there were great variations between the optimized geometries of the ground state and excited states. They could be due to the presence of components of solvent in a real solution that stabilized the excited states, leading to reduce the excitation and emission energies in the experiments.