Interaction in the ternary complexes of HNO3···HCl···H2O: a theoretical study on energetics, structure, and spectroscopy.

Ternary complexes of HNO(3)···HCl···H(2)O were investigated by ab initio calculations with aug-cc-pVDZ and aug-cc-pVTZ basis sets. The results are analyzed in terms of structures, energetics, and infrared vibrational frequencies. In all minima, neither HNO(3) nor HCl becomes ionized. The contribution of the nonadditivity effect, which is significant for hydrogen-bonded clusters, is bigger for the cyclic structures in which HNO(3) acts as a proton donor to HCl, although the global minimum contains HNO(3) donating its proton to a H(2)O molecule.