A correlated study of linear optical absorption in tetracene and pentacene

In this paper, we report large-scale configuration interaction (CI) calculations of linear optical absorption spectra of tetracene and pentacene. For the purpose, we used Pariser-Parr-Pople (P-P-P) model Hamiltonian and quadruple-CI (QCI) and multi-reference single-double CI (MRSDCI) approaches. The role of Coulomb parameters used in P-P-P Hamiltonian was also examined by considering standard parameters as well as screened set of parameters. Results are presented both for the long- and the short-axis-polarized components of the spectra and wave functions of various excited states have also been analysed.