Parametrization of an empirical correction term to density functional theory for an accurate description of π-stacking interactions in nucleic acids

We present an accurate parametrization of density functional theory augmented with an empirical correction term to describe properly a-stacking interactions in nucleic acids. The approach is based on the popular Perdew-Burke-Ernzerhof (PBE), Becke-Perdew (BP), and hybrid Becke-Lee-Yang-Parr (B3LYP) density functionals augmented by a classical London C6R-6 dispersion term. The novelty of our implementation lies in the accurate tuning of the empirical parameters, included in the f(a)(R) damping function, to reproduce high-level post Hartree-Fock calculations. In particular, we present sets of parameters and the needed code to correct the PBE, BP, and B3LYP results from the Turbomole and ADF packages in connection with basis sets of double and triple quality. The developed approach is validated by comparison with the JSCH-2005 benchmark and with best quality stacking energies reported in the literature for the stacking of H-bonded nucleic acids base pairs.