A TIME-DEPENDENT STUDY OF ELECTRONIC SPECTROSCOPY OF 1, 3, 5-TRANS-HEXATRIENE MOLECULE

Abstract

The electronic absorption spectrum, the relative Raman intensities upon 0-0 excitation, and the resonance Raman excitation profiles of trans-l, 3, 5-hexatriene in the region of the 1 ¹B_u à 1 ¹A_g transition are analyzed on the basis of the structures and vibrational force fields obtained from ab initio molecular orbital (MO) calculations. Our implementation of the time-dependent theory for the fitting of experimental spectra and the simulation of model spectra as well as the quantum mechanical calculation of the model parameters is discussed. The implementation covers all electronic structure approaches which are able to deliver ground- and excited-state energies and transition dipole moments. As a test case we discuss the well-known case of the strongly allowed 1 ¹A_gà1 ¹B_u transition in 1, 3, 5- trans-hexatriene in detail using method ranging from simple single-reference treatments to elaborate multi-reference electronic structure approaches.