Electron binding energies of nucleobases and nucleotides
Electron propagator theory is applied to the calculation and interpretation of electron binding energies of molecular fragments found in nucleic acids. This theory provides a systematic approach to correlation problems in quantum chemistry while retaining a one-electron picture of electronic structure. Photoelectron spectra for the purine and pyrimidine bases found in nucleic acids have been assigned with the aid of calculations that employ an electron propagator approximation that has been developed for the study of large molecules. This method, the partial third-order approximation (P3), has been shown to generate reliable electron binding energies for closed-shell molecules and anions. Correlation corrections to canonical, Hartree-Fock orbital energies are necessary for assignment of cationic states. Electron detachment energies for H2PO4- also have been assigned successfully with the P3 method. These results indicate that the P3 method is a suitable procedure for predicting electron binding energies of nucleotide anions. Correlation effects are important in determining the ordering of final states with holes localized on the phosphate or the base regions in the nucleotide. © 2002 Wiley Periodicals, Inc. Int. J. Quantum Chem. 90.