QUANTUM CHEMICAL DFT CALCULATIONS OF THE LOCAL STRUCTURE OF THE HYDRATED ELECTRON AND DIELECTRON
I. I. Zakharov1,2
1Dal' East Ukrainian National University, Lugansk, Ukraine
2Technological Institute, Severodonetsk, Ukraine
Keywords: quantum chemical DFT and РCM calculations, molecular water clusters (H2О)8, (H2О)8– and (H2О)82–, hydrated electron and dielectron models, supermolecule-continuum approximation
Abstract
The adiabatic bound state of an excess electron is calculated for a water cluster (H2O)8- in the gas phase using the DFT-B3LYP method with the extended 6-311++G(3df,3pd) basis set. For the liquid phase the calculation is performed in the polarizable continuum model (PCM) with regard to the solvent effect (water, e = 78.38) in the supermolecule-continuum approximation. The value calculated by DFT-B3LYP for the vertical binding energy (VBE) of an excess electron in the anionic cluster (VBE (H2O)8- = 0.59 eV) agrees well with the experimental value of 0.44 eV obtained from photoelectron spectra in the gas phase. The VBE value of the excess electron calculated by РСМ-B3LYP for the (H2O)8- cluster in the liquid phase (VBE = 1.70 eV) corresponds well to the absorption band maximum λmax = 715 nm (VBE = 1.73 eV) in the optical spectrum of the hydrated electron ehydr-. Estimating the adiabatic binding energy (ABE) ehydr- in the (H2O)8- cluster (ABE = 1.63 eV), we obtain good agreement with the experimental free energy of electron hydration ΔG2980 (ehydr-) = 1.61 eV. The local model (H2O)82- of the hydrated dielectron is considered in the supermolecule-continuum approximation. It is shown that the hydrated electron and dielectron have the same characteristic local structure: -O-H{}H-O- and -O-H{↓}H-O- respectively.
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