The fluctuating cell model

Let us imagine that the liquid cage is a spherical cavity in a continuous medium. When the molecule is in its centre, the orienting field is equal to zero. At this point the anisotropic part of the rotator-neighbourhood interaction appears only in the case of asymmetrical breathing of the 

It is usually assumed that E increases rather sharply, reaching its maximum value A = (/ )d near the wall. 

It is more difficult to estimate the variation of the orienting field, caused by fluctuations of the neighbourhood configuration. In [18] it 

The rectangular approximation (7.6) of dependence E(r) implies that ts = 0. This simplification being valid only for non-adiabatic interaction, exact knowledge of the time-dependence V(t) is not obligatory. Random walk approximation is quite acceptable. The value Ro/R is a free parameter of the model ( Ro/R 1) and makes it possible to vary the ratio of times 0 tc/to oo. This interval falls into two regions one of them corresponds to impact theory (0 tc/to 1), and the other (1 , tc/t0 oo) to the fluctuating liquid cage. In the first case non-adiabaticity of the process is provided by the condition 

However, in the following we shall restrict ourselves solely to the structural limit 

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