Water molecules vibrational parameters

Table 28 presents structural characteristics of compounds with X Me ratios between 6 and 5 (5.67, 5.5, 5.33, 5.25). According to data provided by Kaidalova et al. [197], MsNbsC Fu type compounds contain one molecule of water to form M5Nb303Fi4-H20, where M = K, Rb, Cs, NH4. Cell parameters for both anhydrous compounds [115] and crystal-hydrates [197] were, nevertheless, found to be identical. Table 28 includes only anhydrous compound compositions because IR absorption spectra of the above compounds display no bands that refer to vibrations of the water molecule... 

The EFG data from the multipole parameters are, in principle, for the static crystal while the spectroscopic data are affected by vibrations. There may therefore by a systematic difference between the two sets of values, which is evident for a number of hydrogen-bonded hydroxyl groups and water molecules studied by Tegenfeldt and Hermansson (1985), but is not apparent in the data in Table 8.3. The EFG values for H atoms in hydrogen-bonds is further discussed in chapter 12. 

Thus there are two factors responsible for the maximum in the solvent entropy and its deviation from the pzc. Those parameters are the different configurations the monomers and dimers are able to assume on the surface of the electrode, and that, as we discussed above, depend on the free energy associated with each configuration [Fig. 6.85(a)]. The second parameter is related to the entropy of libration, i.e., how the water molecules oscillate and how these oscillations arc affected by the electrode charge [Fig. 6.85(b)]. The vibrational movements of the molecule do notgivatly affect the position of the maximum in the entropy-charge curve. 

Atomistic MD models can be extended to the coarse-grained level introduced in the previous section, which is determined by the dimension of the backbone chain and branch. For the precise description of water molecular behavior, simple point charge (SPC) model was adopted (Krishnan et al., 2001), which can be used to simulate complex composition systems and quantitatively express vibrational spectra of water molecules in vapor, liquid, and solid states. The six-parameter (Doh, o , fi, Lye, Lyy, and Lee) SPC potential used for the water molecules is shown in Equation (24) ... 

Incoherent neutron scattering (INS) can be used to study the translational, rotational, and vibrational motion of water protons on a time scale between 10" and 10 s. Thus INS provides data pertinent to the V structure and to the transition from the V structure to the D structure in liquid water. The principal use of INS has been to characterize the translational and rotational motion of water molecules through the interpretation of scattering data with model expressions. The three most important model parameters used are the self-diffusion coefficient, Ds, which can also be measured in an experiment involving isotope-labeled water molecules the residence time of a water molecule, tr, during which it vibrates about a fixed position before jumping to its next position and the correlation time, Ti, which is a time constant for the decay of correlation between the orientation of a water molecule at some initial time and at some later time. ... 

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