Normal coordinate analysis and Nonlinear Optical Response of cross-conjugated system 4,4-Dimethyl Benzophenone.

FT-Raman and IR spectra of the nonlinear optical active crystal, 4,4-Dimethyl Benzophenone (4DMBP) have been recorded and analyzed The equilibrium geometry, harmonic vibrational wavenumbers of 4DMBP investigated with the help of density functional theory (DFT) method. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The calculated hyperpolarizability value shows the nonlinear optical activity of the molecule. The value of HOMO-LUMO energy, Mulliken and the natural charges are calculated and analyzed. The Natural bond orbital analysis confirms the occurrence of intramolecular charge transfer interaction.