Theoretical study of multidimensional proton tunneling in the hydrogen carbonate dimer ion [(HCO 3) 2] 2

Ab initio HF/6-31G ∗∗, MP2/6-31G ∗∗ and Becke3LYP/6-311++G ∗∗ calculations have been carried out for the hydrogen carbonate dimer ion [(HCO 3) 2] 2− for the stable and saddle point structures. The energy barrier for the proton tunneling amounts to 9.3 kcal/mol. The normal mode frequencies have been...

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Bibliographic Details
Published in:Journal of molecular structure 2002-09, Vol.614 (1), p.109-115
Main Authors: Wójcik, Marek J., Tatara, Wiktor, Ikeda, Susumu
Format: Article
Language:English
Subjects:
Energy barrier
Proton tunneling
Tunneling splittings
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Summary:Ab initio HF/6-31G ∗∗, MP2/6-31G ∗∗ and Becke3LYP/6-311++G ∗∗ calculations have been carried out for the hydrogen carbonate dimer ion [(HCO 3) 2] 2− for the stable and saddle point structures. The energy barrier for the proton tunneling amounts to 9.3 kcal/mol. The normal mode frequencies have been computed including modes coupled to the proton tunneling mode. Two-dimensional model potentials, formed from symmetric mode coupling potential (SMC) and squeezed double well potential (SQZ), have been fitted to the calculated energy barrier, geometries and frequencies, and used to analyze proton dynamics. The two-dimensional model PES predicts monotonic increase of the tunneling splitting with the excitation of the planar modes and decrease in tunneling splittings with the excitation of the out-of-plane modes.
ISSN:0022-2860
1872-8014
DOI:10.1016/S0022-2860(02)00251-X