Fig. 4: Flowchart of computational study on the active encounter complex.

The numbers in bold show how many configurations are being carried through the workflow at each stage. a Schematic representations of some of the 1644 input coordinates of the encounter complexes. b Graph showing binding energy as a function of P···B distance calculated using a semi-empirical method. The cut-off of 5 kcal mol^–1 above the global energy minimum is shown by a red dashed line, and all points above this line were discarded. c Graph showing binding energy as a function of P···B distance, calculated using DFT; the 774 data points have converged to 72 distinct clusters. d Three-dimensional plot comparing the binding energy with the S₁ excitation energies and oscillator strengths from TD-DFT. The range of P···B distances for each point is also indicated by the colour chart. e The structure of the only data point that has values from the plot in d that is consistent with the experimentally observed absorbance band; the active encounter complex.