Journal of Physical Chemistry A, Vol.119, No.19, 4450-4456, 2015
Infrared Spectra of HCI(H2O)(n) Clusters from Semiempirical Born-Oppenheimer Molecular Dynamics Simulations
Infrared spectra of HCI(H2O)(n) clusters, with n = 4-10 and 21, are calculated at T = 50 K from semiempirical Born-Oppenheimer molecular dynamics simulations performed with the PM3-MAIS model. The specific focus of this study is on the relationship between spectroscopic features associated with the presence of the excess proton generated by the HCl dissociation as a function of n and the underlying water hydrogen-bonding topologies. Vibrational modes involving the motion of the excess proton are attributed to specific features appearing at similar to 1175 cm(-1) for Zundel-type structures, in the 1670-1800 cm(-1) range for intermediate Zundel-Eigen-type structures, and at similar to 2820 cm(-1) for Eigen-type structures. This broad range of vibrational frequencies correlates with the position of the excess proton within the clusters. Overall, the theoretical predictions are in good agreement with the available experimental data.