Open qualitative interpretation

Qualitatively, the most transparent type of model, as ever, would be a one-electron model that is capable of rendering both the ground state and, to a high degree, its excitation properties. However, in the present case, accommodations are called for, on both aspects, that are not trivial. These we will try to pursue and represent within the present one-electron-type framework as closely as possible. In seeking to develop the present model, we base it as firmly as possible on the available data, optical, photoemission, electrical, structural, etc. Much of this data is still open to interpretation, and many of the interpretations to follow are made in the light of experience gained with transition metal compounds (2). 

It is straightforward to show that the current measured at the SECM tip, when the tip is positioned above the pore opening, is proportional to the rate of transport of the redox molecule inside the pore. This is an important result that is implicitly applied in the qualitative interpretation of SECM images of porous membranes. 

Qualitative interpretation of SECM images of a membrane is generally possible without detailed consideration of how the SECM tip influences the diffusion field around a pore opening. However, more quantitative analyses of pore transport generally require that the SECM tip behave as a noninteracting probe. This means that the rate of consumption of electroactive molecules at the SECM tip must be sufficiently small so that the diffusion field... 

One might argue that such a simplistic, qualitative categorisation of severity and likelihood is open to interpretation and is subjective. Surely the more objective... 

In this chapter, we review quantum chemical theories developed to describe chemical bonding in open-shell (transition metal) compounds. We review some important electronic structure methods that provide us with the central ingredient for an analysis of the chemical bond, the electronic wave function. We then discuss how information from the electronic wave function is extracted for a qualitative interpretation of the electronic structure. For this purpose, different approaches are described to extract local quantities from quantum states. An example is the local spin concept, which can be employed to study spin-spin interactions in terms of a Heisenberg coupling model. Finally, the difficulty of describing electronic structures of open-shell molecules accurately is highlighted as an example. 

In this chapter, we reviewed different quantum chemical approaches to determine local quantities from (multireference) wave functions in order to provide a qualitative interpretation of the chemical bond in open-shell molecules. Chemical bonding in open-shell systems can be described by covalent interactions and electron-spin coupling schemes. For different definitions of the (effective) bond order as well as various decomposition schemes of the total molecular spin expectation value into local contributions, advantages and shortcomings have been pointed out. For open-sheU systems, the spin density distribution is an essential ingredient in the... 

The extreme sensitivity of chemical reaction rates to small changes in the PES confined early applications to semiempirical qualitative interpretations of experimentally measured rates. It is in this interpretive role that TST has had such a pervasive influence in chemistry. As our ability to calculate accurate PESs and to carry out quantum dynamics calculations has improved, the role of TST has evolved. Refinements in TST and in our ability to generate chemically accurate PESs are opening a new era in which we shall predict the rates of chemical reactions from first principles. 

The formation of complexes between olefins and metal halides is particularly well documented for titanium tetrachloride [10, 11, 12] thus my theory can be applied with some confidence to systems which involve this metal halide. I will show that it provides a simple qualitative explanation for observations which have so far remained obscure and affords also a quantitative interpretation which is open to testing once the necessary... 

QUALITATIVE COMMENTS (with 14 mg) I am really quite spacey. I can go from a train of thought straight up into thin air. Then, to get to another one there must be a careful choice of words. Logic has nothing to do with any of it. There is no trace of the MDMA-like magic. This is an interpretive drug, not simply an ASC [altered state of consciousness] opening. ... 

Some general aspects related to the derivation, and interpretations of ELF analysis, as well as some representative applications have been briefly discussed. The ELF has emerged as a powerful tool to understand in a qualitative way the behaviour of the electrons in a nuclei system. It is possible to explain a great variety of bonding situations ranging from the most standard covalent bond to the metallic bond. The ELF is a well-defined function with a nice pragmatic characteristic. It does not depend neither on the method of calculation nor on the basis set used. Its application to understand new bond phenomenon is already well documented and it can be used safely. Its relationship with the Pauli exclusion principle has been carefully studied, and its consequence to understand the chemical concept of electron pair has also been discussed. A point to be further studied is its application to transition metal atoms with an open d-shell. The role of the nodes of the molecular orbitals and the meaning of ELF values below 0.5 should be clarified. 

The analysis of local librations in terms of the few existing tractable theoretical models (e.g., lOM) have shown that although a qualitative agreement can be reached with experiments, the interpretation of the short time dynamic behavior remains an open problem. We think that our methodology could help to clarify some aspects of the experimental observations. 

In conclusion, fluid-rock ratios should be used for a rough calculation to demonstrate open or closed system behavior. These ratios can yield qualitative information on stable isotope fluid-rock exchange. Their use should be limited to cases where continuum mechanics approaches to stable isotope transport are not applicable. This is often the case when field relations do not provide evidence of the geometry of the flow system. But one should keep in mind while interpreting the data, that the values do not correspond to actual, physical fluid amounts, but just represent a measurement of exchange (reaction) progress. 

Figure 3 Surprisal plots (18) for the HF vibrational state distribution from the exoergic H atom abstraction reaction F + (CH,)4C - (CH,),CCH2 + HF(v). (Bottom panel) The observed (by D. J. Bogan and D. W. Setser, J. Chem. Phys. 64 586 (1976)) distribution, P(v), open dots connected by a line, and the (so called, prior) distribution, P (v) full symbols, vs. the HF vibrational energy. The prior distribution is the one expected when all products final states are equally probable (18). The observed distribution is qualitatively different from the prior one and their deviance, the surprisal, —In(P(v)/P"(v)) is plotted vs. E/Ev, where Ev is the HF vibrational energy and E is the total energy, in the upper panel. One can interpret the linear dependence of the surprisal on the HF vibrational energy as reflecting the presence of a quantity which is conserved by the dynamics. (See, for example, ref. (108)). In this sense, surprisal analysis is analogous to the search for quantum numbers that are not destroyed by the intramolecular couplings.

Since the first work by Nikolov et al. [44] in 1981 on the possibility of coexisting states in a soluble surfactant monolayer, mainly qualitative discussions on this subject have been published [39, 45]. The systematic thermodynamic work by Fainerman then gives a new understanding of the surface state of soluble surfactants at liquid interfaces [46, 47, 48, 49] as reviewed recently [50, 51]. The impact of these new ideas on adsorption dynamics is immense and up to now has been started only. It appears to be possible to answer to many open questions still existing in the interpretation of surfactant adsorption layer dynamics, and even of protein layers. 

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