A study on the effects of electron correlation, basis set incompleteness and superposition effects in modeling of hydrogen bonding interactıons between water molecules

Abstract

Hydrogen bonding interactions between water molecules are of primary importance not only for understanding the structure of water which is of vital importance for life but also as being a very suitable model in order to reveal the fundamental essentials in determining the appropriate theory level for the electronic structure calculations to be performed for this purpose. Of course, one should consider many factors in modeling of the hydrogen bonded systems, however, the electron correlation effect and the basis set incompleteness and superposition effects are undoubtedly the most prominent ones. To determine the roles of these three main factors in calculation of the structural parameters for water and its most stable dimer and trimer forms, we systematically performed a series of geometry optimization and Hessian calculations using the Hartree-Fock and Density Functional Theory based methods and basis sets of different types and sizes.