The geometries of Phenothiazine, N-Methylphenothiazine and their radical cations have been optimized by using INDO series methods. The neutral molecules are butterfly fold and the radical cations are planar. On the basis of optimized geometries, the charge densities, spin densities, bond orders and electronic spectra of above four molecules and cations have been calculated. The spectra have been assigned theoretically, at the same time, the red shift of spectral band from molecules to cations have been discussed. All calculated results are in good agreement with experimental results.

Key words: PHENOTHIAZINE, ELECTRONIC STRUCTURE, CHARGE DENSITY, PHENOTHIAZINE P, ELECTRONIC SPECTROSCOPY, FREE RADICALS, BOND ORDER, SPIN DENSITY