Features Of Electron Density Distribution Research Articles

Particle Aggregation Effect on Electron Density Distribution and Propagation of Electron Avalanche

Particles will aggregate in the presence of dense mist in the wet electrostatic precipitator (WESP), and larger size particles with changed distribution make discharge more significant. This article puts forward the simulation of corona discharge with the existence of particle aggregation effect, which shows the characteristics of electron density distribution during the propagation. Besides, we also provide propagation patterns of branching and quenching phenomenon of plasma channels in the presence of particle aggregation. The results indicate that particle aggregation will considerably influence the plasma patterns. When the electron avalanche reaches the particle distributing areas, there will be several plasma channels formed and a narrow diffusion radius around the aggregated particles. When particles gather around the electrode, which means dense particle distribution, corona quenching happens with dense particle distribution.

Experimental studies of charge density distribution in the crystals of cytisine and N-methylcytisine. Inside the Fake Tobacco

The high-resolution X-ray data for two bioactive molecules: cytisine (1) and its N-methyl derivative (2) have been collected up to sinθ/λ = 1.12 Å−1 for 1 and 1.0 Å−1 for 2. This data was used for modeling of the fine features of electron density distribution, including bonding density and electron lone pairs. The quality of the model was checked by, e.g., rigid bond test and RDA analysis. The topological analysis (gradient field analysis) has been also performed for both inter- and intramolecular interactions. In case of 1 a number of intermolecular interactions, from relatively strong N-H···O hydrogen bonds to weak H···H contacts was found, and their topological features were analyzed. For N-methyl derivative, only few intermolecular bonding contacts were found. The analyzed features show that besides the structural similarities of both alkaloids, the electron density distribution and consequently all its derivatives differ quite significantly in places.

Understanding the structure of salicyl hydrazone metallocomplexes: crystal structure, AIM and Hirshfeld surface analysis of trichloro-(N-salicylidenebenzoylhydrazinato-N,O,O′)-tin(IV)

The results of detailed experimental and theoretical study of chemical intra- and intermolecular bonding of salicyl hydrazone complex with SnCl3 are described. The chemical bonding pattern in the crystal and isolated molecule is described in terms of Bader’s “Atoms in Molecules” (AIM) theory. Analysis of AIM charges has revealed that amount of charge transferred from ligand to SnCl3 moiety is equal to ≈ 0.3 e that leads to significant redistribution of bond lengths as compared to other tin(IV) salicyl hydrazonates. Comparison of geometry and characteristics of electron density distribution indicates the weakening of coordination Sn–O and Sn–N bonds in isolated molecule in comparison with crystal up to 10 kcal/mol. This effect was explained by the intermolecular H···Cl bonding. According to the Hirshfeld surface analysis, these interactions have the most pronounced contribution to the crystal packing energy. The significance of the present article lies in both the detailed inspection of the crystal packing effect on the coordination bonds of the tin(IV) atom and intermolecular interactions governing the supramolecular self-assembly of hydrogen-bonded chains by means of specific interactions and π···π stacking.

Topological characteristics of electron density and magnetic anisotropy in MgB2

Electron density of MgB2 and hypothetical clusters {Mg14B24} was calculated and studied with quantum chemical methods based on the Density Functional Theory. Topological characteristics of electron density distribution are shown to be related to the anisotropy of local induced magnetic fields in {Mg14B24}. Our data correlate with experimental anisotropy of upper critical fields in MgB2 in the vicinity of the phase transition into the superconducting state.

Topological Characteristics of Electron Density Distribution in SSXY → XSSY (X or Y = F, Cl, Br, I) Isomerization Reactions

The reactions of SSXY to XSSY (X or Y = F, Cl, Br, I) have been studied at B3LYP/6-311++G(2df) and MP2/6-311++G(2df) levels based on B3LYP/6-311++G(2df) optimized geometries. There are two pathways (X or Y atom transferring) for each reaction of SSXY to XSSY(X or Y = F, Cl, Br, I). The "Atoms in Molecules" theory has been applied to analyze the topological characteristics of electron density distribution along the reaction path. (a) The S-S-X or S-S-Y ring structure transition region (STR) is contributed to S(1)-X or S(1)-Y bond formation and S(2)-X or S(2)-Y bond annihilation. The STR and structure transition state (STS) are defined. (b) Comparing the two pathways of each SSXY --> XSSY (X, Y = F, Cl, Br, I) reaction, X or Y atom transferring, the broader the STR is, the later the STS appears, and the pathway is easier. (c) When X linked to the same S site of a three-member ring (S-S-F, S-S-Cl, S-S-Br, or S-S-I), the ring STR becomes broader and the STS appears later according to the sequence of X = F, Cl, Br, and I. And in these cases, for exothermic reactions, the higher the DeltaE(P-->TS1) is, the broader the STR is and the later the STS appears. (d) When the same Y atom linked to different three-member-ring S-S-X, the STR becomes broader and the STS appears later according to the sequence of X = F, Cl, Br, and I in the ring. And in these cases, for exothermic reactions, the lower the DeltaE(P-->TS2) is, the broader the STR is and the later the STS appears.

Ｘ線回折法および第一原理計算法による無機結晶の結晶構造および電子構造に関する研究

Crystal structures and electron density distributions of some manganese and cobalt oxide materials have been studied by the maximum entropy method using single-crystal X-ray diffraction data measured at room temperature. The nature of chemical bonding in these oxides is understood from the present structural and electron density analyses. The features of electron density distribution obtained theoretically by FLAPW calculations for these oxides were in good agreement with the present experimental observations.

Analysis of the changes on the potential energy surface of Menshutkin reactions induced by external perturbations

A quantitative analysis of the changes induced by solvation and static uniform electric fields on the potential energy surface of the S N2 Menshutkin-type reaction between ammonia and methyl chloride has been performed with the help of different indexes. These indexes have been defined to account for the structural and electronic degree of advance of the transition state with respect to the reactant complex and ion pair product through the use of geometrical parameters, dipole moments and electron density distributions. Indexes reveal that external perturbations yield transition states which are both electronically and structurally advanced as compared to the transition state in the gas phase. The overall study is complemented with HOMO-LUMO orbital considerations, quantification of the global charge density redistributions by means of quantum molecular self-similarity measures and an analysis of the topological features of electron density distributions.

On some features of electron density distributions in unsaturated hydrocarbons

A comparative analysis of electron density distributions derived from ab initio MO calculations was carried out for substituted ethylenes, substituted benzenes, 4-substituted styrenes, 4-substituted β,β-difluorostyrenes, and ions of allyl and trimethylenemethyl types. Changes in the atomic effective charges due to substitution or due to a direct variation in the number of electrons within a system were considered. Linear relationships were found between the π and σ components of the charge changes on an unsaturated carbon atom of a carbon chain. The regression coefficients proved to be negative. The regularities were found to be invariant with respect to both the level of ab initio calculation (3G, 4-31G, 6-31G, 6-31G ∗∗ and 6-311++G ∗∗) and the definition of the atomic charge (Bader's criterion or the Mulliken approach). Data from ab initio MO calculations reported in the literature were used.

Quantum chemical study of molecular components of the organic superconductor (BEDT-TTF) 2I 3

The equilibrium structures of (BEDT-TTF) 2I 3 crystal molecular components have been determined within the semiempirical SCF MO LCAO method in the all-valence-electron MNDO approximation, the specific features of electron density distribution in these systems are considered, and their main energy characteristics are defined.

Oxygen disorder in the fluorite-type conductors ( Bi2O3) 1− x( Gd2O3) x by X-ray and EXAFS analyses

The structure refinements were carried out for the fluorite-type compounds of (Bi 2O 3) 1−x(Gd 2O 3) x with x=0.10, 0.20 and 0.25 by X-ray single crystal method. The displacement of oxide ions from the normal tetrahedral site decreases with increasing Gd 2O 3 content and is zero at about 32 m/o Gd 2O 3. No appreciable difference in profile and distance of the Bi-O peak in the Fourier transform of the EXAFS on the Bi L 3-shell absorption is observed for the compounds with x=0.10 and 0.30, exhibiting a contrast to a difference in the features of electron density distribution by X-ray diffraction.

The electronic structure of complexes of vinyl pyramides with metal halides and their crosslinking capability

The electronic structure of vinyl pyridines and their complexes with zinc halides has been calculated by a semi-empirical approximation of the Malliken-Ruedenberg method. An attempt was made to explain some physico-chemical properties of vulcanizates based on SKMS-90 and SKEP rubbers with complexes of vinyl and methylvinylpyridines with zinc halides using the calculated characteristics of electron density distribution.