“…57,58 We chose oB97X-D, since it is an improved, range-separated version of the Becke's original 97 functional 59 that includes both long range correction to the non-Coulomb part of exchange functional and second order dispersion correction, and has been used in a previous similar study on biologically-relevant hydrogen-bonded complexes. 60 Furthermore, a benchmarking of the performance of DFT functionals for studying the optimized geometry, stability and cooperativity of DNA triplexes has shown that the results of the parent B97-D functional are consistent with higher theoretical levels. 61 The dispersion correction within the oB97X-D was implemented using the Grimme's 'DFT-D2' model, 62 albeit with a different damping function and unscaled dispersion correction to model the correct asymptotic pairwise vdW potentials.…”