Basis Set Superposition Error on Structures and Complexation Energies of Organo-Alkali Metal Iodides

Abstract

Theoretical studies have been performed to study the binding characteristics of the alkali metal iodides, M-I (M = Li, Na, K), to poly(ethylene oxide) (PEO, I), poly(ethylene amine) (PEA, II) and poly(ethylene N-methylamine) (PEMA, III) via the B3LYP method. In this study, two types of complexes, singly-coordinated systems (SCS) and doubly-coordinated systems (DCS), were considered, and dissociation energies (ΔE D ) were calculated both with and without basis set superposition error (BSSE). Two types of counterpoise (CP) approach were investigated in this work, but the ΔE D values corrected by using the function CP (fCP) correction exhibited an unusual trend in some cases due to deformation of the sub-units. This problem was solved by including geometry relaxation in the CP-corrected (GCP) interaction energy. On the other hand, the effects of the BSSE on the structures were very small when the complexes were re-optimized on the CP-corrected (RCP) potential energy surface (PES), even if the bond lengths between X and M + (d x-M +) and between M + and I - (d M + -I -) were slightly lengthened. Therefore, neither the GCP nor RCP corrections made much difference to the dissociation energies.