Theoretical investigations for the molecular structures and binding energies for C₆H₆(H₂O)_n, (n = 1–7) complexes

Abstract

The geometrical parameters, vibrational frequencies, and dissociation energies for (H₂O) _n and C₆H₆(H₂O) _n (n = 1–7) clusters have been investigated using density functional theory (DFT) with various basis sets. The highest levels of theory employed are B3LYP/aug-cc-pVTZ for optimization and MP2/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ for binding energy. The harmonic vibrational frequencies and IR intensities are also determined at the various levels of theory to confirm whether the hydrogen-bonded structure of water complex (W _n , n = 1–7) is affected by the presence of benzene. The effect of benzene on the OH stretch modes of benzene–water complex (BW _n , n = 1–7) is observed in the π-hydrogen bonded OH stretch. For each of the BW _n clusters the intensity of this mode is increased significantly due to charge transfer/polarization interactions and the frequency shifts from W _n to BW _n are in the range of 40–60 cm⁻¹. The calculations give the binding energies of 2.58, 4.20, 3.27, 3.00, 3.42, 4.14, and 5.49 kcal/mol for BW₁–BW₇, respectively after ZPVE and 50%-BSSE corrections.

Keywords:

• benzene-water cluster
• binding emergy
• B_z–(H₂O) _n
• B3LYP
• MP2

Acknowledgements

This paper was supported by Hannam University in 2009 and also by the Korean Council for Education, grant funded by Korean Government (MOEHRD) for 2008 Domestic Faculty Exchange.