In search of CS2(H2O)(n=1-4) clusters

Area of Science:

• Computational Chemistry
• Atmospheric Chemistry
• Physical Chemistry

Background:

• Carbon disulfide (CS(2)) is a volatile compound with potential atmospheric relevance.
• Understanding the interactions between CS(2) and water is crucial for atmospheric modeling.
• Small clusters of CS(2) and water (CS(2)(H(2)O)n) can form in the atmosphere.

Purpose of the Study:

• To computationally determine the stable structures and thermochemistry of CS(2)(H(2)O)n clusters for n=1-4.
• To evaluate the suitability of different computational methods for studying these van der Waals complexes.
• To predict the atmospheric concentrations of these clusters under relevant conditions.

Main Methods:

• Utilized Gaussian-3 (G3) and Møller-Plesset perturbation theory with augmented correlation-consistent basis sets (MP2/aug-cc-pVnZ) for calculations.
• Employed extensive molecular dynamics searches followed by geometry optimizations.
• Calculated scaled harmonic and anharmonic vibrational frequencies.

Main Results:

• Identified multiple stable isomers for CS(2)(H(2)O)n clusters (n=1-4), including dimers, trimers, tetramers, and pentamers.
• MP2/aug-cc-pVDZ method showed good agreement with experimental data for the dimer, highlighting the necessity of diffuse functions.
• The G3 method was found unsuitable for these sulfur-containing van der Waals complexes.
• Predicted atmospheric concentrations of CS(2)(H(2)O) and CS(2)(H(2)O)(2) clusters to be substantial (10^5 and 10^2 clusters/cm^3, respectively).

Conclusions:

• The MP2/aug-cc-pVDZ method is reliable for modeling CS(2)-water interactions.
• Larger CS(2)(H(2)O)n clusters are predicted to exist in the atmosphere at detectable concentrations.
• Computational insights are provided for interpreting experimental data from molecular beam studies.