Intriguing relations of interaction energy components in stacked nucleic acids.

Major components of the interaction energy that define several approximate levels starting from second order Möller-Plesset theory were studied for 58 stacked nucleic acid dimers. They included typical B-DNA and A-DNA structures, and selected published geometries. A survey of the various terms yields an unexpected correlation between the Pauli exchange and dispersion or correlation terms, which holds for each class of similar planar geometries and for various basis sets. The geometries that exhibit these correlations span a specific range of molecular overlaps when compared to a model benzene-pyridine stacked dimer. Also, the relationship between electrostatic interactions and MP2 stabilization energies reported earlier is confirmed and a prediction interval of practical relevance is estimated.