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Extremal properties

The functionals Fik i 2k) play a central role in stationary direct perturbation theory. Fq iPq) has been called the Levy-Leblond functional [23], since its stationarity condition is the LLE. For 4( 2) th name Hylleraas-Rutkowski functional has been suggested [23], since this belongs to the class of Hylleraas functionals of second-order perturbation theory, and since it has first been proposed by Rutkowski [73, 74] in a slightly different form. [Pg.718]

We express now q(V o) and 4( 2) in terms of the upper and lower components 2fc and X2k- From now on we use the tilde to indicate trial functions, to distinguish them from their exact counterparts without a tilde. [Pg.718]

We have already mentioned in subsection 2.3 that Fq consists of two parts, one Foi which is bounded from below, and one F02 which is bounded from above. If one imposes wq = 0 one achieves that Fq is bounded from below. [Pg.719]

Approximate solutions of the DE based on stationarity of the functional (353) were, for a long time, plagued by the possibility of variational collapse related to the lack of an upper-bound property. An analysis [35, 36] has revealed that the variational collapse arises whenever one fails to account for the correct nrl. If one imposes the correct nrl, for which there are various possibilities [36], deviations from an upper bound behavior occur at most to 0(c ). In DPT it is sufficient to satisfy the excict relation between xo and pq in order to reduce deviations from an upper bound behavior to 0(c ). The remaining deviations can be minimized by satisfying the exact relation between X2 and 2 to a sufficient accuracy. [Pg.719]

In stationary DPT we automatically care for the correct relation between X2 and i.e. we do exactly, what is done approximately in nonperturba-tive calculations by imposing the so-called kinetic balance [75]. [Pg.719]


As further research on fullerenes and carbon nanotubes materials is carried out, it is expected, because of the extreme properties exhibited by these carbon-based materials, that other interesting physics and chemistry will be discovered, and that promising applications will be found for fullerenes, carbon nanotubes and related materials. [Pg.86]

Cluster analysis is important in all situations where homogeneity of data on the one hand and latent structures on the other hand play a significant role in evaluation and interpretation of analytical results. This applies in particular for single objects with extreme properties like outliers, hot spots etc that can easily be recognized being singletons among clusters. [Pg.260]

In this manner, we have arrived at the Pernal nonlocal potential [81]. It can be shown, using the invariance of Vee with respect to an arbitrary unitary transformation and its extremal properties [13] or by means of the first-order perturbation theory applied to the eigenequation of the 1-RDM [81], that the off-diagonal elements of Uee may also be derived via the functional derivative... [Pg.405]

In the study by Parrott et al. [7], a generic PBPK model was applied to predict plasma profiles after intravenous and oral dosing to the rat for a set of 68 compounds from six different chemical classes. The compounds were selected without particular bias and so are considered representative of current Roche discovery compounds. The physicochemical properties of the compounds are rather different from those of marketed compounds in particular they have higher lipophilicity (mean logP = 4) and lower aqueous solubility as well as a tendency to be neutral at physiological pH. The more extreme property values can present experimental determination challenges and so for consistency all predictions were made on the basis of calculated lipophilicity and protein binding while in vitro... [Pg.232]

Gailitis, M. (1965). Extremal properties of approximate methods of collision theory in the presence of inelastic processes. Sov. Phys. JETP 20 107-111. [Pg.411]

Ceulemans and Fowler [29] have derived the extremal properties of the APES surface of the G <%> (g h) system. There are four types of extrema T minima (with a orbits), D3 minima (with /3 orbits), D3 saddle points (with y orbits) and D2 saddle points (with S orbits). For a dominant JT stabilization from the G mode, the system has T minima (a orbits) only. For a dominant H mode, the system has D3 minima (/3 orbits). The result of the linear problem shows the possibility of a non-degenerate ground state derived from D3 well states. Thus here we consider only the situation when H modes dominate. [Pg.97]

Figure 25 shows all the non-Kekuleans with extremal properties (A = Amax) to h = 10. Only the first 18 systems overlap with those of Fig. 24. For h = 11 the non-Kekuleans with extremal properties which have A = 3, are too many (374 systems cf. Table 25) to be reproduced here. But for h = 12 this type of benzenoids have A = 4 and there are only 14 of them, which are shown in Fig. 26. Figure 25 shows all the non-Kekuleans with extremal properties (A = Amax) to h = 10. Only the first 18 systems overlap with those of Fig. 24. For h = 11 the non-Kekuleans with extremal properties which have A = 3, are too many (374 systems cf. Table 25) to be reproduced here. But for h = 12 this type of benzenoids have A = 4 and there are only 14 of them, which are shown in Fig. 26.
Diamond, which is the hardest known material, is a natural choice for tribological application. In fact, this has been one of the major motivating factors to develop the synthesis of this unique allotrope of carbon in the thin film form. Today, diamond thin films and coatings are considered to be technologically important to a wide variety of applications due to their remarkable combination of extreme properties. [Pg.331]

Table 2. The Extreme Properties of Diamond Compared to Competing Materials and the Possible Areas of Application" ... [Pg.347]

In this section we study among other topics the processes that involve a difference in temperature between a system and the surroundings with which it interacts. This matter seems not to have received sufficient attention in the literature, even though such a difference is needed in any process that involves a transfer of heat. The discussion is much facilitated by the introduction of a deficit function at various stages of the derivation. These deliberations then lead quite naturally to the generation of a variety of useful functions of state and to a study of their extremal properties. [Pg.48]

Construction of Functions of State and their Extremal Properties... [Pg.53]

Class 4 The carbides of this class do not possess the extreme properties of the interstitial carbides. For example, whereas titanium carbide is not attacked by water or HQ even at 600°C, these carbides are decomposed by dilute acids (Fe3C and NisC) or even water (Mn3C). Although the carbon is present as discrete C atoms the products include, in addition to hydrogen, complex mixtures of hydrocarbons. [Pg.761]

One may construct pair functions from a single Slater determinant 4> or from a post-Hartree-Fock wave function I. At first glance the former choice does not look very useful, since for all information is based on the one-electron functions, so why use a more complicated description in terms of 2-electron functions Nevertheless the study of pair functions at the independent particle level has both an intrinsic interest and is useful for the preparation of their use at a correlated level [5], Like the spin-orbitals cpt associated with the Slater determinant to corresponding pair functions ipp. are not uniquely defined and one can transform a given set unitary transformation to an equivalent set. One can establish uniqueness — or at least reduce the arbitrariness — by requiring certain extremal properties of the pair functions. This led us to the concept of extremal electron pairs, studied in detail in Part 1 of this series [5]. [Pg.22]

The basidomycetous yeast Candida antarctica produces two different lipases, A and B. This yeast was originally isolated in Antarctica with the aim of finding enzymes with extreme properties. Both the lipase A and lipase B have been purified and characterized. The two lipases are very different. The lipase B is a little less thermostable and is less active toward large triglycerides but very active... [Pg.67]

Extreme properties requirements for electromigration, conductivity, stress, grain-size, purity, reflectivity, etc. [Pg.26]

In considering abrasion, it will be noted that while actual abrasion loss is a phenomenon involving extreme properties at the surface, layers of vulcanizate immediately contiguous are subjected to many cycles of increasing stress before they are abraded, during which chain-length adjustment develops continuously. [Pg.61]

Table 2.17 gives the ranges of mechanical performance for PVC products. It contains a range of properties found in published data, which means that some more extreme properties can be obtained from PVC but they were not found in the available literature. The information in Table 2.17 contains data for rigid, semirigid, and flexible PVC to show the range of properties that can be obtained. [Pg.38]

The polarization characteristics of monochromators have important consequences in the measurement of fluorescence anisotropy. Such measurements must be corrected for the varying efficiencies of each optical component this correction is expressed as the G-factor (Section 10.4). However, the extreme properties of the concave gratings (Figure 2.11) can cause difficulties in the measurement of fluorescence polarization. For example, assume that the polarization is to be measured at an excitation wavelength of 450 nm. The excitation intensities will be nearly equal with the excitation polarizers in each orientation, which makes it easier to compare the relative emission intensities. If the nission is unpdarized, the relative intensities of the parallel (U) and perpendicular (X) excit ion will be nearly equal. However, suppose the excic ion is at 340 nm, in which case the intensities the... [Pg.34]

Natural diamond has been used by man since at least biblical times, not only as a gem but also, due to its extreme properties relative to other materials, as an abrasive and even as a medicine in crushed form, a panacea for all ills . It is not intended here to enter the debate concerning the crystallization of natural diamond. Some general... [Pg.485]

Superhard compounds are obviously formed by a combination of the low atomic number elements boron, carbon, silicon, and nitrogen. Carbon-carbon as diamond, boron-nitrogen as cubic boron nitride, boron-carbon as boron carbide, and silicon-carbon as silicon carbide, belong to the hardest materials hitherto known. Because of their extreme properties and the variety of present and potential commercial applications, silicon carbide (SiC) and boron carbide (B4C) are, besides tungsten carbide-based hard metals, considered by many as the most important carbide materials. [Pg.131]

Here = 0, 1, 2, 3, 4, 5, and each of these values is associated with a characteristic shape of the circular coronoid. These shapes were already known at least to Balaban (1971), who investigated their important role in the studies of annulenes cf. also a later work in this area (Cyvin SJ, Brunvoll and Gutman 1990). The same shapes are also encountered under the studies of certain primitive single coronoids called hollow hexagons (Cyvin SJ, Brunvoll and Cyvin 1989d Cyvin SJ, Brunvoll, Cyvin, Bergan and Brendsdal 1991), where the extremal property = hOj ax( ) corona hole is of interest. A detailed treatment of this topic is offered in Vol. [Pg.111]

Water is a liquid with extreme properties. If ion-pairs are significant interfacial forces, then it is the high relative permittivity which causes weakening. If physical adsorption is the mechanism of adhesion, then it is the high surface tension of water (see Table 9), which enables it to displace adhesives from metallic surfaces. [Pg.13]

In this section we will investigate the different adiabatic surfaces for electronic orbital doublets and triplets. The treatment is limited to so-called ideal JT systems, i.e. systems with only one JT active mode for each allowed symmetry representation of [Tf - Ai. Although non-ideal or multimode JT problems give rise to more complicated surfaces, it is interesting to note that their extremal properties are similar to those of the corresponding ideal problems [22], Hence as far as the applicability of the epikernel principle is concerned, the neglect of the multimode effect is not expected to affect the conclusions of the present treatment. [Pg.139]

There is a vast literature in mathematics and in chemistry about the Randic index. Eminent mathematicians like Erdos and Bollohas already paid attention to this index at the end of the 20th century. Gutman and others [58,61,62], have found many extreme properties and bounds for this index. Many chemists and biologist have found an immeasurable amount of applications for this index. [Pg.164]

Now from all solutions in plane (5, s) we ll consider only those ones which have extremely properties, namely, their phase velocity c, amplitude a and mean flow rate qo are maximal at every fixed wave number s. We refer to this solutions as dominating waves. From Figure 6 it is clear that at (5 = 0.15 the set of dominating waves includes 4 pieces belonging to described families 7a, 7, 7c,i 7c,2- There are jumps of the dominating waves parameters at values of s dividing one piece from the other. [Pg.205]


See other pages where Extremal properties is mentioned: [Pg.7]    [Pg.8]    [Pg.312]    [Pg.80]    [Pg.143]    [Pg.218]    [Pg.66]    [Pg.138]    [Pg.332]    [Pg.363]    [Pg.389]    [Pg.250]    [Pg.718]    [Pg.3]    [Pg.64]    [Pg.211]    [Pg.683]    [Pg.209]    [Pg.164]    [Pg.100]    [Pg.635]    [Pg.152]   


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