Molecular motion potential governing

Molecular and laser spectroscopic approaches arc making possible a deeper resolution of the dynamics of atomic and molecular motions and the potential energy surfaces governing energy transference within a molecule or group of molecules as chemical bonds are made and broken. 

Fig. 1. An illustration of the potential governing molecular motion in a system. The nucleus may hop between different potential wells, and in addition oscillate within a well. The often-used Markov model assumes that nuclei hop between discrete sites and that the length of time taken to hop is very small compared with the residence time in each site. Such a model can only account effectively for hops between the minima of the potential wells in this illustration diffusion within wells cannot be treated properly.

The behavior of coupling constants as a function of x is qualitatively very similar for the different radicals a(C) is always positive and increases with x due to the progressive contribution of carbon s orbitals to the singly occupied molecular orbital (SOMO). The effect is similar for a(F) and a(H), but since a(H) is negative for the planar conformation (due to first order spin polarization) the absolute value of a(H) decreases up to x 10° and next increases. This allows to discuss vibrational averaging effects simply in terms of the potential governing the out of plane motion. 

Molecules, reorienting in the hat well, belong to the main fraction of the fluids under consideration. This fraction comprises, in both water and ice, about 70% of all molecules. An underlying molecular mechanism, which governs the librational band, can be interpreted as follows. During the mean lifetime Tor, a dipole performs in the hat well on average about two (in water) and a half (in ice) libration cycles. In the case of water this motion is rather free, since a large part of the hat well constitutes a flat bottom (see Fig. 21b). In the case of ice, librations are more restricted. Indeed, as seen in Fig. 21a, the potential bottom is rather narrow. 

The motion of the molecular system under the influence of the potential is determined by the equations of dynamics. Consequently the shape of the computed PES governs entirely this motion. As explained in the previous section, since... 

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