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A comparative ab initio study of Br2*- and Br2 water clusters
A K Pathak1, T Mukherjee, D K Maity
1Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400085, India.
The Journal of Chemical Physics
|January 21, 2006
Summary
This study investigates hydrated bromine dimer (Br2) and its anion (Br2*-) clusters using computational methods. The excess electron significantly alters hydration structures and electronic properties, matching experimental UV-VIS spectra.
Area of Science:
- Computational Chemistry
- Physical Chemistry
- Quantum Chemistry
Background:
- Microhydration of halide dimers is crucial for understanding solvation effects.
- The impact of excess electrons on hydrated species requires detailed investigation.
Purpose of the Study:
- To explore the structural and electronic properties of Br2*-.nH2O and Br2.nH2O clusters.
- To elucidate the influence of an excess electron on the microhydration of bromine dimer.
Main Methods:
- Ab initio calculations using a nonlocal density functional (Becke's hybrid exchange-correlation functional) and a 6-31++G(d,p) basis set.
- Geometry optimizations without symmetry restrictions.
- Excited-state calculations and UV-VIS spectra simulation.
Main Results:
- Br2*-.nH2O clusters exhibit symmetrical double hydrogen-bonding.
- Br2.nH2O clusters (n>=2) show a Br+-Br- ionic character due to water molecule orientation.
- Calculated vibrational frequencies indicate significant shifts from isolated water modes.
- Simulated UV-VIS spectra for Br2*-.10H2O agree well with experimental data for Br2*- in solution.
Conclusions:
- An excess electron profoundly impacts the hydration structure and electronic properties of bromine dimer clusters.
- The theoretical model accurately reproduces experimental observations of Br2*- in aqueous environments.