Nonadditive effects in the mixed trimers of HCl and methanethiol.

Ab initio and density functional theory calculations with aug-cc-pVDZ and aug-cc-pVTZ basis sets have been performed on the HCl-CH3SH dimer and HCl-(CH3SH)2 and (HCl)2-CH3SH trimers. Structures, energetics, and infrared frequencies are calculated. The results are discussed in terms of the cooperativity effect which is a characteristic of H-bonded systems and compared to oxygen-containing analogs of the same trimers, HCl-(CH3OH)2 and (HCl)2-CH3OH, which have been published recently.