title: Low-Lying π* Resonances of Standard and Rare DNA and RNA Bases Studied by the Projected CAP/SAC-CI Method.
abstract: Low-lying π* resonance states of DNA and RNA bases have been investigated by the recently developed projected complex absorbing potential (CAP)/symmetry-adapted cluster-configuration interaction (SAC-CI) method using a smooth Voronoi potential as CAP. In spite of the challenging CAP applications to higher resonance states of molecules of this size, the present calculations reproduce resonance positions observed by electron transmission spectra (ETS) provided the anticipated deviations due to vibronic effects and limited basis sets are taken into account. Moreover, for the standard nucleobases, the calculated positions and widths qualitatively agree with those obtained in previous electron scattering calculations. For guanine, both keto and enol forms were examined, and the calculated values of the keto form agree clearly better with the experimental findings. In addition to these standard bases, three modified forms of cytosine, which serve as epigenetic or biomarkers, were investigated: formylcytosine, methylcytosine, and chlorocytosine. Last, a strong correlation between the computed positions and the observed ETS values is demonstrated, clearly suggesting that the present computational protocol should be useful for predicting the π* resonances of congeners of DNA and RNA bases.
authors.affiliation: SOKENDAI, the Graduate University for Advanced Studies , Nishigonaka, Myodaiji, Okazaki 444-8585, Japan.|Institute for Molecular Science and Research Center for Computational Science , Nishigonaka, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kanazawa
authors.affiliation: SOKENDAI, the Graduate University for Advanced Studies , Nishigonaka, Myodaiji, Okazaki 444-8585, Japan.|Institute for Molecular Science and Research Center for Computational Science , Nishigonaka, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ehara
authors.affiliation: Department of Chemistry and Physics, Southeastern Louisiana University , SLU 10878, Hammond, Louisiana 70402, United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Sommerfeld
mesh_terms: D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*
chemical_list: D012313:RNA; D004247:DNA