Correlation functions normalized flux

The transmission coefficient k was calculated from a series of transition-state trajectories by monitoring the recrossings ( = St) that occur as a function of time until each trajectory is finally trapped in the product or reactant well. The normalized reactive flux-correlation function x(t) defined in Eq. 19 was constructed from this set of trajectories 131 the result is shown in Fig. 29. From its initial value, equal to the. transition-state result, ic(<) decreases rapidly until it becomes approximately constant for an extended period. The ra-... 

Figure 29. Value of the reactive flux-correlation function (/) versus time the function is normalized to the transition-state-theory value (see the text).

The activation free energy AA can be used to compute the TST approximation of the rate constant = Ce, where C is the preexponential factor. Because not every trajectory that reaches the transition state ends up as products, the actual rate is reduced by a factor k (the transmission coefficient) as described earlier. The transmission coefficient can be calculated using the reactive flux correlation function method. " " " Starting from an equilibrated ensemble of the solute molecules constrained to the transition state ( = 0), random velocities in the direction of the reaction coordinate are assigned from a flux-weighted Maxwell-Boltzmann distribution, and the constraint is released. The value of the reaction coordinate is followed dynamically until the solvent-induced recrossings of the transition state cease (in less than 0.1 ps). The normalized flux correlation function can be calculated using " ... 

An interesting peak heat-flux phenomenon is observed when liquid droplets impinge on hot surfaces. Experiments with water, acetone, alcohol, and some of the Freons indicate that the maximum heat transfer is observed for temperature excesses of about 165°C, for all the fluids. The peak flux is a function of the fluid properties and the normal component of the impact velocity. A correlation of experimental data is given in Ref. 30 as... 

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