Big Chemical Encyclopedia

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

Articles Figures Tables About

Local potentials

IHP) (the Helmholtz condenser formula is used in connection with it), located at the surface of the layer of Stem adsorbed ions, and an outer Helmholtz plane (OHP), located on the plane of centers of the next layer of ions marking the beginning of the diffuse layer. These planes, marked IHP and OHP in Fig. V-3 are merely planes of average electrical property the actual local potentials, if they could be measured, must vary wildly between locations where there is an adsorbed ion and places where only water resides on the surface. For liquid surfaces, discussed in Section V-7C, the interface will not be smooth due to thermal waves (Section IV-3). Sweeney and co-workers applied gradient theory (see Chapter III) to model the electric double layer and interfacial tension of a hydrocarbon-aqueous electrolyte interface [27]. [Pg.179]

For a local potential V(r) which supports bound states of angular momentum i and energy < 0, the phase shift linij Q (Ic)) tends in the lunit of zero collision energy to n. When the well becomes deep enough so as to introduce an additional bound level = 0 at zero energy, then linij ... [Pg.2034]

One current limitation of orbital-free DFT is that since only the total density is calculated, there is no way to identify contributions from electronic states of a certain angular momentum character /. This identification is exploited in non-local pseudopotentials so that electrons of different / character see different potentials, considerably improving the quality of these pseudopotentials. The orbital-free metliods thus are limited to local pseudopotentials, connecting the quality of their results to the quality of tlie available local potentials. Good local pseudopotentials are available for the alkali metals, the alkaline earth metals and aluminium [100. 101] and methods exist for obtaining them for other atoms (see section VI.2 of [97]). [Pg.2218]

In a diabatic representation, the electronic wave functions are no longer eigenfunctions of the electronic Hamiltonian. The aim is instead that the functions are so chosen that the (nonlocal) non-adiabatic coupling operator matrix, A in Eq. (52), vanishes, and the couplings are represented by (local) potential operators. The nuclear Schrddinger equation is then written... [Pg.279]

The generally applicable relations for a two-conductor model are derived in the following section. For simplicity, local potential uniformity is assumed for one of the two conductor phases. Relationships for the potential and current distributions, depending on assumed current density-potential functions, are derived for various applications. [Pg.549]

Electronics has, in fact, been a very fertile area for SEM application. The energy distribution of the SEs produced by a material in the SEM has been shown to shift linearly with the local potential of the surface. This phenomenon allows the SEM to be used in a noncontact way to measure voltages on the surfaces of semiconductor devices. This is accomplished using energy analysis of the SEs and by direedy measuring these energy shifts. The measurements can be made very rapidly so that circuit waveforms at panicular internal circuit nodes can be determined accurately. [Pg.81]

Attard GA, Ahmadi A. 1995. Anion-surface interactions. Part 3 N2O reduction as a chemical probe of the local potential of zero total charge. J Electroanal Chem 389 175-190. [Pg.239]

This type of fully local potential has some limited use, e.g., to consider adsorption in a slowly varying external potential. It fails, however, to describe the most important phenomena such as surface tension and adsorption at most types of interfaces. These phenomena reflect in a fundamental way the nonlocal interactions in the fluid. The most obvious nonlocality of the free energy arises due to the range of the attractive or soft interactions represented by the second term in the equation of state, —The corresponding potential energy can be obtained by the functional... [Pg.100]

E is the energy of the electrons, VB is the vacuum energy, m is the mass of the electron and % is Planck s constant divided by In. (VB E) is the local potential barrier height, which to a first approximation is the work function for metal surfaces this is typically 4-5 eV. [Pg.36]

The next step is crucial. We have shown above that the exact wave functions of noninteracting fermions are Slater determinants.12 Thus, it will be possible to set up a noninteracting reference system, with a Hamiltonian in which we have introduced an effective, local potential Vs(r) ... [Pg.59]

However, one feature of the HF potential is that it is not a local potential. In the case of perfect data (i.e. zero experimental error), the fitted orbitals obtained are no longer Kohn-Sham orbitals, as they would have been if a local potential (for example, the local exchange approximation [27]) had been used. Since the fitted orbitals can be described as orbitals which minimise the HF energy and are constrained produce the real density , they are obviously quite closely related to the Kohn-Sham orbitals, which are orbitals which minimise the kinetic energy and produce the real density . In fact, Levy [16] has already considered these kind of orbitals within the context of hybrid density functional theories. [Pg.267]

Bryant This has not been studied in Drosophila. Several Dig-like MAGUKs have been picked up in a yeast two-hybrid screen using as bait the Erb-B4 receptor (Garcia et al 2000), which is the only one of the mammalian EGF receptor family that has a C-terminus predicted to bind to PDZ domains. This interaction could be involved in controlling receptor localization. Potentially it is the same kind of interaction. [Pg.197]

Reactants AB+ + CD are considered to associate to form a weakly bonded intermediate complex, AB+ CD, the ground vibrational state of which has a barrier to the formation of the more strongly bound form, ABCD+. The reactants, of course, have access to both of these isomeric forms, although the presence of the barrier will affect the rate of unimolecular isomerization between them. Note that the minimum energy barrier may not be accessed in a particular interaction of AB+ with CD since the dynamics, i.e. initial trajectories and the detailed nature of the potential surface, control the reaction coordinate followed. Even in the absence (left hand dashed line in Figure 1) of a formal barrier (i.e. of a local potential maximum), the intermediate will resonate between the conformations having AB+ CD or ABCD+ character. These complexes only have the possibilities of unimolecular decomposition back to AB+ + CD or collisional stabilization. In the stabilization process,... [Pg.82]

Schnitker et al. s (1986) finding, based on classical molecular dynamics simulation, of a large density (4.4 ml-1 at 10°C) of local potential minima qualifying as trapping sites. [Pg.271]

Reorientations produce characteristic maxima in the relaxation rate, which may be different for the various symmetry species of CD4. The measured relaxation rates exhibit dependence on two time constants at low temperatures, but also double maxima for both relaxation rates. We assume that molecules may move over some places (adsorption sites) on the cage walls and experience different local potentials. Under the assumption of large tunnelling splittings the T and (A+E) sub-systems relax at different rates. In the first step of calculation the effect of exchange between the different places was considered. Comparison with experimental data led to the conclusion that we have to include also a new relaxation process, namely the contribution from an external electric field gradient. It is finally quite understandable to expect that such effect appears when CD4 moves in the vicinity of a Na+ ion. [Pg.172]

Rotators in the solid state experience a well defined potential, with a depth and symmetry resulting from interactions with surrounding ions or molecules. Combined translation and rotation of CD4 lead to a much less specified meaning of the apparent activation energy obtained experimentally. Obtained values indicate that we have different values of the activation energy for different temperature ranges. Therefore their relation to local potentials at the walls of cages requires a further study. [Pg.172]

The description of phase transitions in a two-dimensional dipole system with exact inclusion of long-range dipole interaction and the arbitrary barriers AUv of local potentials was presented in Ref. 56 in the self-consistent-field approximation. The characteristics of these transitions were found to be dependent on AU9 and the number n of local potential wells. At =2, Tc varies from Pj /2 to Pj as AU9... [Pg.25]


See other pages where Local potentials is mentioned: [Pg.169]    [Pg.170]    [Pg.2049]    [Pg.2208]    [Pg.2884]    [Pg.498]    [Pg.117]    [Pg.54]    [Pg.57]    [Pg.59]    [Pg.1238]    [Pg.599]    [Pg.39]    [Pg.232]    [Pg.238]    [Pg.238]    [Pg.284]    [Pg.59]    [Pg.209]    [Pg.64]    [Pg.95]    [Pg.166]    [Pg.25]    [Pg.690]    [Pg.104]    [Pg.172]    [Pg.207]    [Pg.22]    [Pg.25]    [Pg.43]    [Pg.45]   
See also in sourсe #XX -- [ Pg.81 ]

See also in sourсe #XX -- [ Pg.12 , Pg.47 ]

See also in sourсe #XX -- [ Pg.12 , Pg.47 ]

See also in sourсe #XX -- [ Pg.3 ]




SEARCH



Action potential local anesthetics affecting

Benzoic Acid and Aniline Analogues with Potential Local Anaesthetic Profile

Bound states in a local, central potential

Calculation of Electrostatic Potentials from Strictly Localized Fragments

Density functional derivative Frechet, local potential

Double well potentials, local control theory

Electrochemical potential of H, localized and delocalized

Equivalent local potential

External local potential

Full-potential local orbital method

Functional derivatives and local potentials

H-Bond Asymmetric Local Potentials

Kohn-Sham local potential

Kohn-Sham orbitals and potentials for beryllium by means of local scaling transformations

Local analyses redox potential

Local average ionization potential

Local coherent potential approximation

Local electric charge density potential

Local electrical potential

Local electrostatic potential

Local exchange potential

Local field factors potentials

Local ionization potential

Local ionization potential map

Local mean field potential

Local potential function, kinetic energy

Local reactivity indexes electronic chemical potential

Many-electron local potential

Many-electron local potential calculation

Molecular potential local

Non-local potential

Optical potential equivalent-local

Potential Sources of Assistance through Local Colleges and Universities

Potential energy surfaces local dynamics

Potential energy surfaces stationary points, localization

Potential energy, local minima

Potentials local modes

Protein structure local backbone potential

Redox potential local charges

Relativistic electron in a local, central potential

The Kohn-Sham Potential is Local

The Schrodinger equation for a local, central potential

The local complex-potential (LCP) model

© 2024 chempedia.info