Theoretical Study of the Potential Energy Surfaces of the Van Der Waals H2O-X2+ (X = Cl or Br) Complexes
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- 作者：Tahra Ayed ; Ramó ; n Herná ; ndez Lamoneda ; Kenneth C. Janda
- 刊名：Journal of Physical Chemistry A
- 出版年：2008
- 出版时间：January 31, 2008
- 年：2008
- 卷：112
- 期：4
- 页码：722 - 727
- 全文大小：160K
- 年卷期：v.112,no.4(January 31, 2008)
- ISSN：1520-5215
文摘
An ab initio study of the interactions between H2O and Cl2+ and H2O and Br2+ has been performed. Wepresent calculations using both the UMP2 level and the UCCSD(T) level of correlation with the aug-cc-pVTZ basis. The aug-cc-pVQZ basis was tested for selected geometries and was found to yield results similarto the smaller basis. For the H2O-Cl2+ cation, a C2v structure has been identified as the minimum, with De= 6500 cm-1 (78 kJ/mol). A low-lying excited state has De = 6000 cm-1 (72 kJ/mol). The adiabatic andvertical ionization energies of the complex are 10.7 and 11.0 eV, compared to the experimental adiabaticvalue, 11.5 eV, for free chlorine. For the H2O-Br2+ cation, the calculations are more subtle due to second-order Jahn-Teller effects and result in a Cs structure at the minimum, with De = 6300 cm-1 (75 kJ/mol),yielding an adiabatic ionization energy of 9.9 eV compared to the corresponding experimental value, 10.5eV, for free bromine. The relatively large binding energies give rise to strong normal mode couplings suchthat the halogen stretching mode becomes mixed with the water bending and other intermolecular modes,resulting in very large frequency shifts. Vertical ionization energies and ion vibrational frequencies also arereported and used to discuss possible experiments to obtain more precise data for each of the complexes.