Dipole moment water

Figure A2.4.10. Orientational distribution of the water dipole moment in the adsorbate layer for tlu-ee...

The physical properties (boiling point solubility m water dipole moment) of alkynes resemble those of alkanes and alkenes... 

The results in Table V illustrate that MD studies, compared to the MC results in Table IV, facilitate the investigation of transport and time-dependent properties. Also, they show that use of the MCY potential leads to very large density oscillations and increasing water density near the surfaces. This appears to be a serious drawback to the use of the MCY potential in simulations of interfacial water. Results from the investigations using the ST2 potential show that interfacial water density is approximately 1.0 g/cc, with a tendency for decreased density and hydrogen bonding near the surfaces. As in the MC simulations, orientations of the water dipole moment are affected by the presence of a solid/liquid interface, and an... 

The behavior of such a large system as a pore formed by a bacterial porine (E. coli OmpF) has been simulated in a lipid bilayer of palmitoyloleoylphosphatidylethanola-mine (POPE) [95]. Despite the use of united atoms, the final system of the trimeric porin embedded into 318 POPE molecules and solvated with water consisted of more than 65 000 atoms in total. During the 1 ns of the MD simulation the trimeric structure remained stable, with almost all flexibility in the loops and turns outside the 3-strands. The movement and orientation of the water molecules was investigated in detail. As found in case of the pore formed by the hexameric LS3 helix bundle [90], the diffusion of the water was decreased to about 10% of that of bulk water. Some ordering of the water molecules was evident from the average water dipole moments, which showed a strong dependence on the vertical position within the porine. 

Recent sequential molecular dynamics/quantum mechanics (MD/QM) calculations of the water dipole moment [51] using a polarizable model for water [52] indicate that the average dipole moment in the liquid is not dependent on the number... 

The relationship between the local structure of the HB network and electronic properties was investigated and it was concluded that the water dipole moment and electron binding energies exhibit some dependence on the local environment of the network. Specifically, the dipole moment in liquid water increases with the number of H bonds, although it is not dependent on the role played by the water molecule as H donor or acceptor. On the other hand, the lbi EBE increases when the interaction with the surrounding water molecules involves directly the oxygen atom of the central water molecule, which then plays the role of H bond acceptor. 

Fig. 2.63. Dependence of ion-HjO interaction on ion-0 distance. 1 Symmetric H O molecule orientation (ion-0 vector coincides with the water dipole moment direction) 2 lone pair-to-ion orientation, (a) Na, (b) K (1 A = 100 pm). (Reprinted from G. G. Malenkov, Modelsforthe Structure of Hydrated Shells of Simple Ions Based on Crystal Structure Data and Computer Simulation, in The Chemical Physics of Solvation, Part A, R. R. Dogonadze, E. Kalman, A. A. Komyshev, and J. Ulstrup, eds., Elsevier, New York, 1985.)...

Figure 2. Water Dipole Moment as a Function of Concentration.

The "group" dipole moment of the amide functional group is calculated from dielectric constant data and found to be 2.0 Debyes in dry polymer films and 2.1 Debyes in films conditioned at 40% RH. The small increase in "wet" films is consistent with the water absorption data indicating that the effective water dipole moment decreases in the presence of amide groups. 

Surface Potential Studies. Surface potential measurements were made on all compounds at the same time surface pressure was measured. Since it is preferable to have a parameter which reflects only changes in the fatty acid and surface water dipole moments and not changes resulting from merely increasing the number of dipoles per unit area, surface potential values, AV, were converted to an apparent surface dipole moment, (i), where... 

The orientational structure of water near a metal surface has obvious consequences for the electrostatic potential across an interface, since any orientational anisotropy creates an electric field that interacts with the metal electrons. The anisotropy of the orientational distribution of water has therefore been investigated in most studies of aqueous systems in inhomogeneous environments. The results can be summarized as follows. In almost all studied systems, a preference for orientations in which the water dipole moment is more or less parallel to the interface has been observed. The driving force for the avoidance of orientations that can lead to surface electrostatic... 

Kemp, D. A., Gordon, M. S. (2008). An Interpretation ofthe Enhancement of the Water Dipole Moment Due to the Presence of Other Water Molecules,/ Phys. Chem. A, 112,4885-4894. 

Gregory, J. K., et al.. The water dipole moment in water clusters. Science, 1997. 275C5301), 814-817. 

Together with other water properties, the temperature change of the water dipole moment was investigated by McGrath et al. in 2006 [95]. The authors observed... 

The interfacial water structure at different alkali halide salt surfaces can be further studied from the water dipole moment distributions at the crystal surface. Figure 4.6 describes the water dipole... 

FIGURE 4.6 Water dipole moment density distribution along LiCl (a), NaCl (b), KCl (c), and RbCl (d) salt surface normal. (From Du, H. and Miller, J. D. J. Phys. Chem. C, 111 10013, 2007c. With permission.)... 

Interfacial water structures at selected phyllosilicate minerals, including talc, kaolinite, and sepiolite, are analyzed in terms of water distribution and water dipole moment orientation. The behavior of water molecules and wetting characteristics at these surfaces are explained in terms of the mineral surface structure. Simulation details have been reported in previous pnblications (Du and Miller 2007a, 2007b Miller et al. 2007 Nalaskowski et al. 2007). 

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