Asymmetric Short-Range Interactions

The short-range interactions include the vdW force limited to the 0 H bond [18], the exchange interaction to the H-0 polar covalent bond [19], and the Coulomb repulsion between the lone and the shared electron pairs attached to the adjacent oxygen ions, represented by the following potentials  

With least number of adjustable parameters, the Morse potential for the exchange interaction suffices. One can hardly tell which potential is better than the other as we are concentrated about the equilibrium coordinates of bond length and bond energy, disregarding shapes of the potential curves. Because of the short-range nature of the interactions, the solid lines are only effective in the shaded area 

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In this section we develop a more accurate implementation of short-range interactions, while keeping electrostatics at the mean field level. Such a procedure introduces asymmetric treatment of different parts of a pair potential. To formally set up and justify this asymmetry of methods, we consider the scaled pair potential. 

Relation (4) takes into account only the distribution of the two monomeric units in terms of triads and the short range interactions between these monomeric units. Of course, in the [ m], local conformational changes of units are included but no asymmetric structures of macromolecular chains are considered. 

Abstract Hydrogen bonds form a pair of asymmetric, coupled, H-bridged oscillators with ultra short-range interactions, whose asymmetric relaxation and the associated binding electron entrapment and nonbonding electron polarization discriminate water and ice from other usual materials in the structure order and the physical anomalies. 

Fig. 33.3 Forces and relaxation dynamics of the segmented 0 H-0 bond. Asymmetric and coupling relaxation dynamics of the master-slave-segmented 0 H-0 bond in water ice under applied stimulus. Short-range interactions of intramolecular H-O bond exchange interaction, intermolecular 0 H non-bond vdW interaction (broken red lines), interelectron-pair Coulomb repulsion (broken white lines), forces of Coulomb repulsion /q, deformation recoveryand the force driving relaxation acting on the electron pairs (small dots). H atom is the coordinate origin. Because of the strength disparity, Mi] > lAdnl the Coulomb repulsion makes the Adg and the A l shift in the same direction by different amounts (Reprinted with permission from [14])...

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. 23. (CH3CN)2Cu2Ru6C(CO),6, 20 (50). The distorted octahedral Ru6C core is capped by two directly bonded copper atoms [Cu-Cu = 2.693(1) A], one on an Ru3 face, the second on the CuRu2 face so formed. The Ru-Ru distances range from 2.798(1) to 3.072(1) A (mean 2.89 A). Ru-Q.rtjrte distances range from 2.031(4) to 2.073(4) A (mean 2.05 A). There are thirteen terminal carbonyls, and three asymmetrically bridging Ru-Ru edges. No Cu-CO contacts are short enough to imply bonding interactions.

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