Quantum Theory of Atoms in Molecules/Charge-Charge Flux-Dipole Flux interpretation of fundamental vibrational intensity enhancements on H-bond formation of water trimer

The Quantum Theory Atoms in Molecules/Charge-Charge Flux-Dipole Flux model was used to investigate electronic structure variations associated with intensity changes for water trimer vibrations. The total of 440 km mol(-1) experimental intensity for the symmetric stretches amounts to an average contribution of 147 km mol(-1) per hydrogen bond. The calculated QCISD/cc-pVTZ value is 274 km mol(-1). The largest changes on complex formation occur for the charge, charge flux and their interaction. The hydrogen-bonded hydrogen atoms account for 99% of the total intensity of the two strongest symmetric stretches, mostly owing to mechanical vibration factors. (C) 2014 Elsevier B.V. All rights reserved.