Autocorrelation function direct damping

C. The Rosch and Ratner Directly Damped Quantum Autocorrelation Function... 

To answer this question, we eomputed the resonance positions and widths of HCO 41] and HN2,[42] using both doubled and undoubled autocorrelation funetions obtained from the damped Chebyshev propagation. The results indieated tiiat the enforeed doubling of the autocorrelation function yields no appreeiable differenees in both positions and widths of the narrow resonances when compared with those obtained from a directly calculated autocorrelation function. The differences are plotted in Fig. 1 for the low-lying resonances of HN2. The largest differences are for resonanees with widths on the order of a few hundred wave numbers.[42]... 

In polymers, due to the constraint resulting from the connectivity of the chain, the local motions are usually too complicated to be described by a single isotropic correlation time x, as discussed in chapter 4. Indeed, fluorescence anisotropy decay experiments, which directly yield the orientation autocorrelation function, have shown that the experimental data obtained on anthracene-labelled polybutadiene and polyisoprene in solution or in the melt cannot be represented by simple motional models. To account for the connectivity of the polymer backbone, specific autocorrelation functions, based on models in which conformational changes propagate along the chain according to a damped diffusional process, have been derived for local chain... 

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