AB-INITIO POTENTIAL-ENERGY SURFACES FOR THE I(P-2(3 -LEFT-RIGHT-ARROW-I(P-2(1/2))+O-2(X-3-SIGMA(-)(G)) ENERGY-TRANSFER PROCESS/

Ab initio electronic structure calculations have been used to investig ate the electronic energy transfer process I(P-2(3/2)) + O-2(a(1)Delta (g)) double left right arrow I(P-2(1/2)) + O-2(X(3)Sigma(g)(-)). Poten tial 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 wi th the above reactants and products were all found to be non-bonding. Shallow Van der Waals minima were predicted at long range. Surface cro ssings were found at energies below the I(P-2(3/2)) + O-2(a(1)Delta(g) ) asymptote. It is probable that these crossings are responsible for t he efficient transfer of electronic energy in this system. (C) 1998 El sevier Science B.V. All rights reserved.