Fig. 4: Nuclear quantum effects and proton delocalization in a BI hexamer. | Nature Communications

Fig. 4: Nuclear quantum effects and proton delocalization in a BI hexamer.

From: Anomalous rotational-symmetry breaking in proton arrangement of surface-confined cyclic hydrogen bonds revealed by atomic force spectroscopy

Fig. 4

a, b Probability distributions (a) and free-energy profiles (b) for the proton along the reaction coordinates in the BI dimer at 50 K, obtained from PIMD (red lines) and AIMD (blue lines) simulations. Inset: representative PIMD configuration with a delocalized proton (red spheres). c Time traces of NN′ distances and RC of BI dimer obtained from PIMD simulations. The variation of the average NN′ distance (red line) and RC with time and their quantum fluctuations (grey shading) are shown in (c). Orange shading marks intervals with RC ≈ 0 accompanied by shortened NN’. d Representative LAMMPS-PIMD snapshots of the −8.5°-L-hexamer on Ag(111) surface showing coexisting localized and delocalized protons (red spheres). e, f Proton probability distributions and free-energy profiles along RC in L3-L4 (e) and L4-L5 (f) within the hexamer at 5 K. Source data are provided as a Source Data file.

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