The electronic absorption spectra of ClOCl and ClClO. An ab initio EOM-CCSD(T) investigation

Equation-of-motion coupled cluster calculations with singles and doubles (EOM-CCSD) and with noniterative inclusion of triples (EOM-CCSD(T)) have been carried out with the POL1 basis set to iinvestigate the excited states of ClOCl and ClClO. Both isomers have five excited states with excitation energies at wavelengths longer than 200 nm. These states are valence excited states which arise from transitions which remove electron density from the π system and place it into σ, or from electron excitation within the σ framework. The results of these calculations are used to assign the bands in the recently reported experimental spectra of these molecules.