Charge Localization in Stacked Radical Cation DNA Base Pairs and the Benzene Dimer Studied by Self-Interaction Corrected Density-Functional Theory

The incomplete cancellation of the electron self-interaction can be a serious shortcoming of density-functional
theory especially when treating odd-electron systems. In this work, several popular and potentially viable
correction schemes are applied in order to characterize the electronic structure of stacked molecular pairs,
consisting of a neutral molecule and adjacent radical cation, as a function of separation distance. The unphysical
sharing of the positive charge between adjacent molecules separated by 6−7 Å is corrected for by applying
a new empirical scheme proposed by VandeVondele and Sprik [Phys. Chem. Chem. Phys. 2005, 7, 1363]
with a unique choice of parameters. This method is subsequently applied to characterize the electronic structure
of two neighboring guanines excised from a canonical Arnott B-DNA structure and will be used in future
investigations of certain model DNA fibers.