Some computational aspects of the characterization of the complex hydrogen bond network dynamics using power spectral analysis are discussed.In the case of hydrogen-bonded liquids,the tagged molecule potential energy is shown to be a useful quantity for capturing the behavior of the networked liquid on different lengths and time scales.The computation of the tagged potential energy for rigid-body effective pair potentials,such as the TIP5P-E and SPC-E models,is discussed.The more structured nature of the TIP5P-E potential,compared to the SPC/E potential,shows up as differences in the high-frequency librational band of the power spectra of the tagged molecule potential energies.The static distributions of the tagged molecule potential energies are also more structured in the case of TIP5P-E,rather than SPC/E,water.The overall behavior of the key power spectral features remains the same in both the models.The possibility of detailed characterization of the power spectrum,and therefore of the underlying dynamics,using a model-based parametric fitting procedure for the power spectra is also discussed.We show that a parametric fitting can allow one to test alternative models of the dynamics underlying the liquid state dynamics.
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