DFT Studies on Excited State Geometry, Vibrational Modes, NMR, Molecular Orbital and Mulliken Charges of Laser Dye

Abstract

The laser dye 2, 5-diphenyl-1, 3, 4-oxadiazole (PPD), which has many uses in science and technology, has been the topic of DFT investigation using the Gaussian 16. Laser dye geometry has been optimised at the 6-311G++(d, p)/B3LYP basis set using the DFT approach. A graphic representation of the overall energy variation as a function of optimisation phases is shown. The DFT approach yielded a ground state dipole moment of 3.61 Debye. A computational technique called TD-DFT at 6-311++G (d, p)/B3LYP basis set has been utilised to analyse the UV-visible spectra of laser dye in ethanol. The eccentric state geometry yielded parameters such as absorption maxima, oscillator strength, and excited-state energy. The dipole moment in the excited state is about 5.11 Debye. The excited state's dipole moment is larger than the ground state's. The DFT and TD-DFT techniques were used to determine the Mulliken atomic charges. Chemical shifts and vibrational modes have been studied using NMR and IR spectroscopy, respectively. Atomic charges and electron densities can be used to determine a molecule's dipole moment and charge distribution. Given the small HOMO-LUMO energy gap, the molecule should be soft. The electrostatic potential map is used to identify the molecule's electrophilic and nucleophilic locations. According to these investigations, the molecule might be used in optoelectronics.