Chemical bond topology

Their chemical bonding topologies can be analyzed as follows ... 

Some examples of bare ionic post-transition metal clusters are depicted in Fig. 3. Their chemical bonding topologies can be analyzed as follows ... 

Log P and MR are considered thermodynamic descriptors, pR a combined thermodynamic and electronic index, and a an electronic property index, E is designed to account for steric effects. Corrections for non-additivity, based upon the chemical bonding topology, have been suggested and used. These include proximity, bond type, ring, and group shape correction features. (8-10)... 

Further analysis of the computed energy parameters either requires some special symmetry such as that found in octahedral BeHe or icosahedral Bi2Hi2 or some further assumptions concerning the chemical bonding topology for less symmetrical systems in order to minimize the number of independent unknowns to be determined. In the cases of BeHe ... 

A more direct rationalization for the anomalous electron counts in isocloso deltahedra describes the chemical bonding topology in isocloso deltahedra in terms of exclusively 3c-2e B-B-B bonds in deltahedral faces without any 2c-2e bonds or two-electron bonds involving more than three orbitals such as the / center two-electron core bonds in the deltahedral boranes (6 < n < 12) discussed above (section... 

Elemental boron exists in a number of allotropic forms of which four (two rhombohedral forms and two tetragonal forms) are well established (Table 5). The structures of all of these allotropic forms of boron are based on various ways of joining B12 icosahedra using the external orbitals on each boron atom. The chemical bonding topology in these B12 icosahedra appears to be exactly analogous to that found in the discrete Bi2Hi2 anion, so that elemental boron provides an example of three-dimensional aromaticity in a refractory material. 

The chemical bonding and the possible existence of non-nuclear maxima (NNM) in the EDDs of simple metals has recently been much debated [13,27-31]. The question of NNM in simple metals is a diverse topic, and the research on the topic has basically addressed three issues. First, what are the topological features of simple metals This question is interesting from a purely mathematical point of view because the number and types of critical points in the EDD have to satisfy the constraints of the crystal symmetry [32], In the case of the hexagonal-close-packed (hep) structure, a critical point network has not yet been theoretically established [28]. The second topic of interest is that if NNM exist in metals what do they mean, and are they important for the physical properties of the material The third and most heavily debated issue is about numerical methods used in the experimental determination of EDDs from Bragg X-ray diffraction data. It is in this respect that the presence of NNM in metals has been intimately tied to the reliability of MEM densities. 

For over a decade, the topological analysis of the ELF has been extensively used for the analysis of chemical bonding and chemical reactivity. Indeed, the Lewis pair concept can be interpreted using the Pauli Exclusion Principle which introduces an effective repulsion between same spin electrons in the wavefunction. Consequently, bonds and lone pairs correspond to area of space where the electron density generated by valence electrons is associated to a weak Pauli repulsion. Such a property was noticed by Becke and Edgecombe [28] who proposed an expression of ELF based on the laplacian of conditional probability of finding one electron of spin a at t2, knowing that another reference same spin electron is present at ri. Such a function... 

Silvi B, Savin A (1994) Classification of chemical bonds based on topological analysis of electron localization functions. Nature 371 683... 

Consequently, it must be emphasized that precautions have to be taken with the conventional rough description of molecules based on the chemical bond pattern. In a molecule that contains at least two atoms which do not belong to the first row of the periodic table, the energy and all the monoelectronic properties are literally spread out over the whole molecule. Obviously, the concept of chemical bond, based as it is on the principle of topological proximity, is inadequate on its own for a correct description of the chemical and physical behavior of such a molecule. 

The basic aspects of the structural systematic and the chemical bonding are discussed as well as ambiguous topological aspects and selected physical properties (magnetism, conductivity) of the respective alloys. 

In general, differences in chemical bonding and electron configuration between carbon atoms and dopants mandate the deviation from the geometric and electronic equilibrium structure of the aromatic layers in CNTs. As a consequence, topological defects such as Stone-Wales defects are formed with increased probability [37]. 

The modem state of EDSA in combination with topological analysis of the ESP and electron density allows to obtain reliable and quantitative information about chemical bonding and properties. 

Chemical Bonding and the Topology of the Total Electron Density Distribution... 

The promolecule density shows (3, — 1) critical points along the bond paths, just like the molecule density. But, as the promolecule is hypothetical and violates the exclusion principle, it would be incorrect to infer that the atoms in the promolecule are chemically bonded. In a series of topological analyses, Stewart (1991) has compared the model densities and promolecule densities of urea,... 

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