Some ab initio thoughts on the bonding in O3H

We study the ground X~2A′′ state of O3H (= OaObOcH) with single (RCCSD(T)) and multi (MRCI) reference correlation methods in order to shed some light on its bonding mechanism in connection with its low dissociation energy and rather long bond distance (OaOb−OcH). For such a task all three dissociation/formation paths were considered (O2 + OH, O + O2H, and O3 + H) and the associated nonadiabatic coupling matrix elements were examined. It appears that the excited states of the above asymptotic fragments participate in the equilibrium wavefunction of O3H in a way that results in a symmetry broken structure.