Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Dynamic polarization theory

The ferroelectric-condensation, dynamic-polarization theory of high temperature superconducting perovskites is, at least, a non-BCS theory. [Pg.128]

The g-tensor components in MgO are in qualitative agreement with the theory, which predicts g = g = 2.0023 and g >9e [2]- The differences between the two sets of constants for the center in CaF2 as presented above may be ascribed to different levels of purity of the crystals used [10]. The dynamic polarization of the F nuclei was studied [10]. [Pg.83]

From SCRP spectra one can always identify the sign of the exchange or dipolar interaction by direct exammation of the phase of the polarization. Often it is possible to quantify the absolute magnitude of D or J by computer simulation. The shape of SCRP spectra are very sensitive to dynamics, so temperature and viscosity dependencies are infonnative when knowledge of relaxation rates of competition between RPM and SCRP mechanisms is desired. Much use of SCRP theory has been made in the field of photosynthesis, where stnicture/fiinction relationships in reaction centres have been connected to their spin physics in considerable detail [, Mj. [Pg.1617]

Pedersen J B and Freed J H 1973 Theory of chemically induced dynamic electron polarization. I J. [Pg.1619]

Wong S K, Hutchinson D A and Wan J K S 1973 Chemically induced dynamic electron polarization. II. A general theory for radicals produced by photochemical reactions of excited triplet carbonyl compounded. Chem. Phys. 58 985-9... [Pg.1620]

In the potential region where nonequilibrium fluctuations are kept stable, subsequent pitting dissolution of the metal is kept to a minimum. In this case, the passive metal apparently can be treated as an ideally polarized electrode. Then, the passive film is thought to repeat more or less stochastically, rupturing and repairing all over the surface. So it can be assumed that the passive film itself (at least at the initial stage of dissolution) behaves just like an adsorption film dynamically formed by adsorbants. This assumption allows us to employ the usual double-layer theory including a diffuse layer and a Helmholtz layer. [Pg.258]

Chandra and his coworkers have developed analytical theories to predict and explain the interfacial solvation dynamics. For example, Chandra et al. [61] have developed a time-dependent density functional theory to predict polarization relaxation at the solid-liquid interface. They find that the interfacial molecules relax more slowly than does the bulk and that the rate of relaxation changes nonmonotonically with distance from the interface They attribute the changing relaxation rate to the presence of distinct solvent layers at the interface. Senapati and Chandra have applied theories of solvents at interfaces to a range of model systems [62-64]. [Pg.415]

Lamoureux G, Roux B (2003) Modeling induced polarization with classical Drude oscillators theory and molecular dynamics simulation algorithm. J Chem Phys 119(6) 3025-3039... [Pg.247]

The brief review of the newest results in the theory of elementary chemical processes in the condensed phase given in this chapter shows that great progress has been achieved in this field during recent years, concerning the description of both the interaction of electrons with the polar medium and with the intramolecular vibrations and the interaction of the intramolecular vibrations and other reactive modes with each other and with the dissipative subsystem (thermal bath). The rapid development of the theory of the adiabatic reactions of the transfer of heavy particles with due account of the fluctuational character of the motion of the medium in the framework of both dynamic and stochastic approaches should be mentioned. The stochastic approach is described only briefly in this chapter. The number of papers in this field is so great that their detailed review would require a separate article. [Pg.173]

In an effort to understand the mechanisms involved in formation of complex orientational structures of adsorbed molecules and to describe orientational, vibrational, and electronic excitations in systems of this kind, a new approach to solid surface theory has been developed which treats the properties of two-dimensional dipole systems.61,109,121 In adsorbed layers, dipole forces are the main contributors to lateral interactions both of dynamic dipole moments of vibrational or electronic molecular excitations and of static dipole moments (for polar molecules). In the previous chapter, we demonstrated that all the information on lateral interactions within a system is carried by the Fourier components of the dipole-dipole interaction tensors. In this chapter, we consider basic spectral parameters for two-dimensional lattice systems in which the unit cells contain several inequivalent molecules. As seen from Sec. 2.1, such structures are intrinsic in many systems of adsorbed molecules. For the Fourier components in question, the lattice-sublattice relations will be derived which enable, in particular, various parameters of orientational structures on a complex lattice to be expressed in terms of known characteristics of its Bravais sublattices. In the framework of such a treatment, the ground state of the system concerned as well as the infrared-active spectral frequencies of valence dipole vibrations will be elucidated. [Pg.52]


See other pages where Dynamic polarization theory is mentioned: [Pg.119]    [Pg.129]    [Pg.119]    [Pg.129]    [Pg.129]    [Pg.154]    [Pg.66]    [Pg.124]    [Pg.356]    [Pg.26]    [Pg.133]    [Pg.293]    [Pg.50]    [Pg.58]    [Pg.189]    [Pg.1383]    [Pg.244]    [Pg.564]    [Pg.855]    [Pg.1590]    [Pg.1781]    [Pg.371]    [Pg.248]    [Pg.150]    [Pg.72]    [Pg.673]    [Pg.192]    [Pg.267]    [Pg.205]    [Pg.256]    [Pg.259]    [Pg.82]    [Pg.4]    [Pg.248]    [Pg.252]    [Pg.340]    [Pg.211]    [Pg.13]    [Pg.108]    [Pg.51]   
See also in sourсe #XX -- [ Pg.118 , Pg.126 ]




SEARCH



Dynamic polarization

Dynamical theory

Dynamics, theory

Polar theory

Polarization theory

© 2024 chempedia.info