Optical and vibrational properties of 1,2-benzenedicarboxylic anhydride.

The solvent-induced changes in the optical and spectroscopic properties of 1,2-benzenedicarboxylic anhydride are studied using time dependent Hartree-Fock and density functional theory calculations within the framework of two reaction field procedures. To investigate the influence of the cavity shape, the Onsager reaction field is compared with the polarized continuum model (PCM). It is observed that solvent polarity has noticeable effects on the vibrational properties as well as the linear and nonlinear optical characteristics of the molecule. Furthermore, the Onsager and PCM procedures may lead to contradicted harmonic vibrational frequencies; in the case of the studied molecule the Onsager model predicts the blue-shifted CH stretching band while PCM leads to red-shifted CH stretching mode.