Ab initio potential energy surfaces for the I(2P3/2)+O2(a 1Δg)⇔I(2P1/2)+O2(X 3Σ−g) energy transfer process

Ab initio electronic structure calculations have been used to investigate the electronic energy transfer processI(2P3/2)+O2(a1Δg)⇔I(2P1/2)+O2(X3Σ−g) .Potential energy surfaces for all states associated with the reactants and products were obtained using CASSCF and CASPT2 methods, including the effective one-electron spin–orbit Hamiltonian. Surfaces correlating with the above reactants and products were all found to be non-bonding. Shallow Van der Waals minima were predicted at long range. Surface crossings were found at energies below the I(2P3/2)+O2(a1Δg) asymptote. It is probable that these crossings are responsible for the efficient transfer of electronic energy in this system.