Radical ions and radicals in electron-irradiated acrylates and N-isopropylacrylamide: a quantum chemical study

The semiempirical quantum chemical methods MNDO, AM1 and PM3 were used to i nvestigate the performance of the single excited configuration interaction (SCI) approximation for calculating low energy excitation energies of open- shell systems. Systematic calculations were done for eight radicals formed by reactions of H-., OH. and e(aq)(-) with various acrylates and N-isopropy lacrylamide. The calculated electronic spectra show a reasonable correlatio n with experimental data for both neutral radicals and radical ions. The AM I as well as the PM3 formalism can be successfully applied to calculate the low energy excited states of these types of open shell systems. The best c orrelation between experimental and calculated excitation energies was obta ined using the PM3 method (correlation coefficient 0.96, overall average er ror 0.16 eV). (C) 1999 Elsevier Science Ltd. All rights reserved.