Frontier molecular orbital analysis for determining the equilibrium geometries of atmospheric prenucleation complexes

A systematic characterization of the frontier molecular orbitals (FMO) of gas‐phase prenucleation complexes between H 2 SO 4 and other molecules present in the atmosphere (NH 3 , H 2 O, (CH 3 )OH, HF, (CH 3 ) 2 PH, (CH 3 )SH) is carried out using the ωB97X‐D/6‐311++(2d,2p) method at the density functional theory level of theory. The FMO theory principles are taken into account to gain insight into the nature of intermolecular interactions. The results show that the highest occupied molecular orbital/lowest unoccupied molecular orbital molecular system characterization can be adopted as a complementary tool of analysis in supporting the study of atmospheric prenucleation processes. It is shown that the stability and the spatial arrangement of molecular systems can be also thought in terms of inter‐ and intra‐molecular energy gaps ΔE HL that play an important role in the development of association processes.