Stacking Energies for Average B-DNA Structures from the Combined Density Functional Theory and Symmetry-Adapted Perturbation Theory Approach

Stacking energies for the ten unique tetramers composed of two complementary base pairs in an average B-DNA arrangement are calculated with the DFT-SAPT variant of intermolecular perturbation theory and compared to spin-component scaled second-order Møller−Plesset theory. The well-defined decomposition of the interaction energy available in DFT-SAPT suggests that at least the first-order electrostatic and exchange and the second-order total dispersion energies have to be accurately modeled to reproduce the different stacking energies of the various base pair steps, while the induction contributions can effectively be accounted for through a scaled dispersion energy.