Benchmark of DFT methods and QTAIM analysis of acetone clusters: Structure, stability and non-covalent interactions

Years of research, laboratory experimentation, and practice have demonstrated that acetone can be safely used in organic and atmospheric chemistry, in various industrial and commercial applications. Therefore, understanding the self-assembly of acetone molecules is crucial to elucidate its solvation properties and intermolecular interactions. This study presents a comprehensive theoretical characterization of the structural and energetic features of pure acetone clusters _n (n = 1 to 8) in the gaseous state. A rigorous computational approach was implemented, integrating a systematic exploration of potential energy surfaces using ABCluster as well as optimization and study of interactions at an advanced theoretical level. The MN12SX-D3 functional, chosen following a careful comparison with 26 other DFT functionals and benchmark DLPNO-CCSD(T1)/CBS calculations, was used. Our results reveal that the stability of the clusters is dominated by antiparallel motifs, stabilized by intermolecular H-C⋯O hydrogen bonds. The study of binding energies (ΔE_n) and electron density configuration (QTAIM) confirms the nature of these non-covalent bonds. A convergence of structural and energetic characteristics is observed for clusters of dimension n≥6. This research provides a fundamental and quantitative description of acetone self-assembly processes, in agreement with existing experimental data. It establishes essential theoretical references for the modeling of carbonyl solvents and their condensed-phase behaviors.