H-Bond Asymmetric Local Potentials

Lagrangian solution to the coupled oscillators enables mapping of the asymmetric, short-range potentials pertaining to the 0 H-0 bond. 

Both oxygen atoms in the O.H-O bond shift initially from their equilibrium (without coulomb coupling) outwardly with respect to the coordination origin (H), lengthening the 0—0 distance by Coulomb repulsion. 

Both oxygen atoms then move toward right along the 0 H-0 bond by different amounts upon being compressed and cooled, toward length symmetrization. The vdW potential Viff) for the 0 H non-covalent bond reaches a valley at — 0.25 eV and the lowest exchangeVyiif) for the H-0 polar covalent bond values at —3.97 eV under compression. 

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With known bond lengths (or density) and vibration frequencies, Lagrangian mechanics maps H-bond asymmetric, local, short-range potentials Water and ice prefer statistically the fluctuated, tetrahedrally coordinated structure with supersolid skin despite the fluctuations in 0 H length and <0 H-... 

Fig. 33.2 Asymmetric, local, short-range potentials for the segmented H-bond. Interactions include the short-range vdW (left hand side) and the exchange (right hand side) interactions and the Coulomb repulsion between electron pairs on adjacent oxygen atoms (Reprinted with permission from [13])...

Fig. 37.4 The asymmetric, local, short-range potentials Vx(r) of the 0 H-0 bond in a Compressed ice (from left to right, P = 0, 5, 10, 15, 20, 30, 40, 50, 60 GPa) and b Cooling ice [1]. Small solid circles in blue represent the intrinsic equilibrium coordinates (length and energy) of the oxygen ions without the Coulomb repulsion (V x = 0, Vc = 0, = 0), and the...

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