Analysis of non-covalent interactions in the acetone-chloroform system by MP2/CBS quantum chemical calculations

We studied the non-covalent interactions present in the acetone-chloroform system at the MP2/Complete Basis Set level of theory. To this end, we did a configurational search for the diverse geometries of (acetone) 2 homodimers, (chloroform) 2 homodimers and acetone-chloroform heterodimers. All the structures we obtained were subjected to full geometry optimization and their vibrational frequencies calculated. The resulting wavefunctions were subjected to Reduced Density Gradient and Non-Covalent Interaction analyses which yielded a variety of critical points. We found that the reported hydrogen bond for the acetone-chloroform dimer likely has a van der Waals component involving interaction between a chlorine in chloroform and a hydrogen in acetone. In addition, we extrapolated energies to the Complete Basis Set limit. The MP2/Complete Basis Set-calculated interaction energies follow the trend (acetone) 2 > acetone-chloroform > (chloroform) 2 . It was also found that MP2/cc-pVDZ severely underestimates the interaction energies as well as predicts the wrong trend, when compared to MP2/Complete Basis Set.