Figure 5.

Top: Structures for the {β-SiW₉} starting and {γ-SiW₉} end points of the metadynamics calculation, with the structures showing the distances W–O1 and W–O2 corresponding to the collective variables. Middle: Free-energy surface obtained from Car–Parrinello metadynamics for the [β-SiW₉O₃₄]^10– to [γ-SiW₉O₃₄]^10– transformation as a function of the two selected CVs. Bottom: Detail of the trajectory of the two CVs during the metadynamics; the red crosses represent the position of the minima and transition structure at 0 K in the CV space. Energies are in kcal·mol^–1 and distances in Å. Color code: W = teal, Si = orange, O = red, K= yellow. Gray polyhedra are used to differentiate W centers belonging to rotated {W₃} triads.