Real-time TD-DFT study on the dioxygen/superoxide radical charge transfer reaction

Superoxide (O-2(center dot-)) is oxygen radical anion that damages biochemical systems. Here I executed real-time computations on the dioxygen/superoxide charge transfer (CT) reaction that is a mode of superoxide radical formation and propagation: O-a(2) + O-b(2)center dot- -> O-a(2)center dot- + O-b(2). Dioxygen/superoxide CT involves a diatomic oxygen dimer encounter complex (EC). I used time-dependent open shell density functional theory (TDODFT)/CAM B3LYP to show that the parallel quartet EC had an optimized contact distance of 2.62 A, and a fast oscillating free radical CT reaction time of 97.2 femtoseconds. (C) 2017 Elsevier B.V. All rights reserved.