Figure 5.

Geometry optimization of van der Waals π-π interaction between butein ring B and superoxide. Initial separation of 3.50 Å, evolves toward σ scavenging, in contrast with all figures in this section (Figure 4). The picture shows the evolution of the DFT process after 100 cycles of geometry optimization, clearly indicating that the result is the capture of H4 by superoxide, confirmed after additional cycles (not shown).