Effects of distortion-rotation of potential energy surfaces on absorption and resonance raman cross sections of trans-stilbene molecule

The time–correlation function formalism has been used to calculate resonance Raman cross sections and electronic absorption spectra of the trans‐stilbene molecule. The multidimensional time domain integrals that arise in these calculations have been evaluated for the cases in which electronic transitions take place between displaced, displaced–distorted, and displaced–distorted–rotated harmonic potential energy surfaces. The effects of distortions and rotations of potential energy surfaces on absorption, and resonance Raman cross sections are investigated quantitatively. The calculated absorption spectra and resonance Raman cross sections have been compared with the experimental results. Finally, resonance Raman excitation profiles have been simulated for five vibrational modes of trans‐stilbene, assuming the displaced–distorted–rotated harmonic oscillator model. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005