Electronic Resonances of Nucleobases Using Stabilization Methods.

The interaction of low-energy electrons with nucleobases is important because of their potential to damage nucleic acids. In this work we investigate several low-lying resonances of nucleobases using quantum chemical methods including static and dynamical correlation coupled with orbital stabilization methods. Specifically, the equation of motion for electron affinities via couple cluster singles and doubles and multireference perturbation theory methods were used, and their performance was explored. Low-lying π* resonances were calculated and compared to previous theoretical and experimental results, showing good agreement for positions and widths. Feshbach/Core-excited resonances generated by attachment of an electron to a ππ* excited state of the bases were also calculated, providing for the first time accurate information for these resonances. Mixing between configurations corresponding to shape and Feshbach/core-excited resonances is present in all nucleobases, which complicates the theoretical treatment and necessitates multiconfigurational approaches for a proper description.