Molecular conformational stability and Spectroscopic analysis of Parared with experimental techniques and quantum chemical calculations

Abstract The complete vibrational assignment and analysis of the fundamental modes of Parared was carried out using the experimental FTIR and FT-Raman data and quantum chemical studies. The observed vibrational data were compared with the wavenumbers derived theoretically from the optimized geometry of the compound from the DFT–B3LYP gradient calculations employing 6-31G(d,p) and 6-311++G(d,p) basis sets. Thermodynamic properties like entropy, heat capacity and enthalpy have been calculated for the molecule. HOMO–LUMO energy gap has been calculated. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis. Important non-linear properties such as electric dipole moment and first hyperpolarizability of Parared have been computed using B3LYP quantum chemical calculations. Finally, the Mulliken population analysis on atomic charges of the title compound has been calculated.