Non-covalent interactions in dimethylsulfoxide (DMSO) clusters and DFT benchmarking

Abstract

Dimethylsulfoxide (DMSO) is one of the most used solvents in industries and in Chemistry. Understanding the dynamics of the solvent is subjected to the understanding of interactions in DMSO clusters. Despite its importance, a very few studies have been reported on DMSO clusters. In this work, we have explored thoroughly the potential energy surfaces (PESs) of the DMSO clusters from dimer to tetramer at the MP2/aug-cc-pVDZ level of theory. In order to understand the non-covalent interactions in DMSO clusters, we have performed a quantum theory of atoms in molecules (QTAIM) analysis. The QTAIM analysis showed that there are eight different types of non-covalent interactions stabilizing the DMSO clusters. The CH⋯O hydrogen bonding and H⋯H bonding are found to be the strongest and the weakest non-covalent interactions in DMSO clusters, respectively. In addition, we have reported the temperature-dependent isomer distribution of all the investigated clusters for temperatures ranging from 50 to 500 K. To allow affordable investigations of medium and large sized DMSO clusters in future investigations, we have assessed the performance of ten functionals of the density functional theory (DFT) in calculating the binding energies of the DMSO clusters. The ten DFT functionals (M05, M05-2X, M06, M06-2X, M08HX, PBE0, ωB97XD, PW6B95D3, APFD and MN15) have been benchmarked to MP2/CBS and DLPNO-CCSD(T)/CBS. The functionals PW6B95D3 and ωB97XD are recommended for further affordable investigations of the DMSO clusters.