Intramolecular forces long-range interaction

In the majority of cases the force associated with the MM interactions is composed of a Coulombic term (typically a long-range correction is applied), non-Coulombic forces (Lennard-Jones 6-12 type potentials are the most commonly used formulation), and intramolecular force field contributions. The QM/MM coupling is composed of the Coulombic interactions with all core (Ni) and layer (N2) atoms plus non-Coulombic forces with all atoms in the layer region (N2). As the latter contributions correspond to the coupling terms in the core and layer regions, no violation of momentum conservation occurs. 

In the regions intermediate between these limiting cases, normal modes of vibration "erode" at different rates and product distributions become sensitive to the precise conditions of the experiment. Intramolecular motions in different product molecules may remain coupled by "long-range forces even as the products are already otherwise quite separated" (Remade Levine, 1996, p. 51). These circumstances make possible a kind of temporal supramolecular chemistry. Its fundamental entities are "mobile structures that exist within certain temporal, energetic and concentration limits." When subjected to perturbations, these systems exhibit restorative behavior, as do traditional molecules, but unlike those molecules there is no single reference state—a single molecular structure, for example—for these systems. What we observe instead is a series of states that recur cyclically. "Crystals have extension because unit cells combine to fill space networks of interaction that define [dissipative structures] fill time in a quite... 

In Chapter 1 we briefly described an interface as a layer with uncompensated intermolecular forces. The thermodynamics of a liquid interfaces covered with a soluble or insoluble monolayer layer has been describe in detail by many other competent authors and we want to present only the thermodynamic basis needed for the subsequent chapters of this book. Let us consider the interface between water and air. The specific properties of the bulk water, e.g. the freezing point, boiling point, vapour pressure, viscosity, cluster formation and hydrophobic bonds, are well described by long and short-range intermolecular forces and strong and weak intramolecular forces. Israelachvili recently (1992) remarked in a short note on the usefulness of this classification, although it is not clear whether the same interaction is counted twice or two normally distinct interactions are strongly coupled. 

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