Molecular orbital theory of the 1<i>L</i> <i>b</i> and 1<i>L</i> <i>a</i> states of indole

Abstract

A comprehensive study of the 1Lb and 1La excited states of indole, using a spectroscopically calibrated semiempirical molecular orbital method [the spectroscopic version of the intermediate neglect of differential overlap-configuration interaction (INDO/S-CI)], is reported. Results from two standard parametrizations and procedures are identified as giving satisfactory agreement with several experimental properties. Diagrams of MOs, π transition densities, and π density changes are provided from these two calculations. In addition, transition energies, oscillator strengths, transition moment directions, dipoles, and two-photon properties are presented for 24 additional calculations representing variations in the key parameters.