• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1267-1271
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• 2002

The conformation dependences of basis set superposition errors (BSSE) for 1,2-difluoroethane (DFE) and 1,2-dimethoxyethane (DME) molecules have been estimated using counterpoise method at the Moller-Plesset second order perturbation (MP2) level of theory with various basis sets, assuming that all BSSE dependences on conformations are due to the change in CC bond. The BSSE on the energy differences between eclipsed and gauche forms of DFE are in the range of 0.2-1.2 kcal/mol and those between local minima, gauche and anti forms, are less than 0.2 kcal/mol. For the larger DME molecule, the BSSE differences between local minima are still less than 0.4 kcal/mol, but may not be ignored compared to the energy differences of 0.2-3.0 kcal/mol between conformers.

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2228-2234
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• 2010

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 (${\Delta}E_D$) were calculated both with and without basis set superposition error (BSSE). Two types of counterpoise (CP) approach were investigated in this work, but the ${\Delta}E_D$ 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.