The spectroscopic FT-IR gas phase, FT-IR, FT-Raman, polarizabilities analysis of Naphthoic acid by density functional methods

The Fourier transform infrared gas phase spectrum of Naphthoic acid (NA) was recorded in the region 4000–400 cm−1. The Fourier transform Raman spectrum and Fourier transform IR spectra of NA were recorded in solid phase. Quantum chemical calculations of energies, geometrical structure, infrared intensities, Raman scattering activities and vibrational wavenumbers of NA in ground state have been carried out by density functional (DFT/B3LYP) and BLYP method with 6-31G(d,p) as basis set. A good correlation was found between the computed and experimental wavenumbers. A detailed interpretation of the infrared and Raman spectra of NA was also reported. The dimer parameters (intermolecular hydrogen bonding) by B3LYP/6-31G(d,p) method are also calculated. The polarizability and Mullikan atomic charges have also been computed using ab inito HF and DFT calculations. Comparison of simulated spectra provides important information about the ability of the computational method to describe the vibrational modes.