Interaction energy contributions of H-bonded and stacked structures of the AT and GC DNA base pairs from the combined density functional theory and intermolecular perturbation theory approach.

Stacked and Watson-Crick structures of DNA base pairs are investigated with the DFT-SAPT variant of intermolecular perturbation theory, yielding a rigorous decomposition of the interaction energy into electrostatic, induction, dispersion, and exchange contributions. Their interplay in the various structures is analyzed. Total interaction energies extrapolated to the complete basis set limit are compared with corresponding second-order Møller-Plesset and estimated coupled-cluster theory results.