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.