Fig. 4: Peak positions of hydrogen densities.
a, Theoretical curves of hydrogen density along the C–H bond. The Coulomb-potential curve in green was calculated from the electron-density curve in yellow (Methods). The peak heights are adjusted for clarity. Vertical lines represent the centre position of the curves and hydrogen nucleus (1.083 Å)25. b,c, Observed hydrogen density along aromatic C–H bonds in the hydrogen-omitted map in the SX (b) and rt-ED (c) structures. Small circles and triangles on the plots represent peak locations, and grey horizontal lines refer to a density threshold level of 1.5σ. d, The same plots as in b and c but for N–H bonds. The density peaks of the hydrogen atoms appear to have shorter bond lengths in the SX structure than in ED.
