eV in the bimolecular complex, essentially the same as the isolated monomers in the equilibrium Figure . Computed ground and excited state energies (eV) for acetone monomer (𝑨𝑨) and the excimer complex ( 𝑨𝑨𝑨𝑨 ), and the intermediate energy terms from multistate energydecomposition analysis (MS-EDA). The energies for the fully delocalized excimer are determined using TDDFT/M06-2X. States shown in the light-yellow background are determined using nonorthogonal state interaction (NOSI) with the excimer geometry, and the excited species are indicated in red. The notations (𝐴𝐴) 0 and (𝐴𝐴) 1 denote the optimized structures for the ground and first excited state of acetone. Energies are given relative to that of acetone in the ground state.