Abstract
Electronic properties of H~2~O~2~(H~2~O)~1–6~ and (H~2~O)~1–7~ clusters are reported. Emphasis was placed on the changes induced by the presence of hydrogen peroxide on the electronic properties of water aggregates. Theoretical results for excitation energies as well as vertical and adiabatic ionization energies are reported. Excitation energies were calculated with time‐dependent density functional theory and equation‐of‐motion coupled cluster with single and double excitations (EOM‐CCSD). A many‐body energy decomposition scheme recently proposed was coupled to the EOM‐CCSD method making possible an accurate prediction of the first vertical excitation energy of peroxide–water clusters. In comparison with water clusters, our results show that the presence of hydrogen peroxide in water clusters is characterized by a [1.5–1.8] eV red‐shift of the first excitation energy. The first excitation is localized on the HOOH moiety, and no significant dependence of the first excitation energy on the cluster size is observed. The differences between vertical and adiabatic ionization energies for both water and hydrogen peroxide–water clusters reflect the feature that ionization leads to proton transfer and to a significant structural and electronic density reorganization. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010