Basis set effect on hydrogen bond stabilization energy estimation of the Watson–Crick type nucleic acid base pairs using medium-size basis sets: single point MP2 evaluations at the HF optimized structures

Abstract

The basis set effect in evaluation of hydrogen bond energies of the Watson–Crick type base pairs between adenine (A) and uracil (U) and between guanine (G) and cytosine (C) was studied from 6-31G to 6-311++G(3df,p) basis set at the second-order Møller–Plesset (MP2) levels of theory using the structures optimized at the Hartree–Fock (HF) level of theory. Both the optimized structures around the hydrogen bonds and the hydrogen bond energies fluctuated largely depending on whether or not one set of the d-type polarization functions was set on the heavy atoms. The effects of the second and third sets of the d-type and first set of f-type polarization functions on the heavy atoms were smaller. Almost the same tendency was observed in the A–U and the G–C base pairs in the fluctuation of hydrogen bond energy depending on the basis set. The hydrogen bond energies of A–U and G–C base pairs calculated at MP2/6-31+(2d′,p′)//HF/6-31G(d,p) were in good agreement with the result of MP2/6-311++G(3df,p)//HF/6-311++G(3d,p).