Ab initio post-HF study of electronic charge density distribution of cyclic (B6C)−2: Concrete evidence of a novel bonding pattern

2007 ◽  
Vol 822 (1-3) ◽  
pp. 116-121 ◽  
Author(s):  
Shant Shahbazian ◽  
Abdolreza Sadjadi
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Ab Initio ◽  
Electronic Charge ◽  
Charge Density Distribution ◽  
Electronic Charge Density

The study on charge-density distribution in TiAl by quantitative electron crystallography method

1995 ◽  
Vol 10 (8) ◽  
pp. 1913-1916 ◽  
Author(s):  
Yu Miao ◽  
Jing Zhu ◽  
X.W. Lin ◽  
W.J. Jiang
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Interatomic Bond ◽  
Electronic Charge ◽  
Electron Crystallography ◽  
Charge Density Distribution ◽  
Electronic Charge Density ◽  
Density Distributions ◽  
Structure Factors ◽  
Equiaxed Grain

Structure factors of μ-TiAl equiaxed grain in TiAl duplex intermetallic compound before and after V-alloying were measured by the quantitative electron crystallography method. Then the structure factors were transferred into charge-density distributions of real space. Comparing the charge-density distributions in γ-TiAl with those in V-alloyed γ-TiAl, it was found that V-alloying with the optimum amount decreases the electronic charge density in the Ti-Ti interatomic bond, and increases the electronic charge density in the Al-Al interatomic bond and Ti-Al interatomic bond. Thus, the anisotropy of charge-density distribution in γ-TiAl equiaxed grain is reduced.

scholarly journals CO2 Electrochemical Reduction by Exohedral N-Pyridine Decorated Metal-Free Carbon Nanotubes

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2703 ◽  
Author(s):  
Giulia Tuci ◽  
Jonathan Filippi ◽  
Andrea Rossin ◽  
Lapo Luconi ◽  
Cuong Pham-Huu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Density Distribution ◽  
Charge Density ◽  
Carbon Nanomaterials ◽  
Electronic Charge ◽  
Charge Density Distribution ◽  
Electronic Charge Density ◽  
Faradaic Efficiency ◽  
Metal Free ◽  
Electrochemical Co2 Reduction

Electrochemical CO2 reduction reaction (CO2RR) to fuels and chemicals represents nowadays one of the most challenging solutions for renewable energy storage and utilization. Among the possible reaction pathways, CO2-to-CO conversion is the first (2e−) reduction step towards the production of a key-feedstock that holds great relevance for chemical industry. In this report we describe the electrocatalytic CO2-to-CO reduction by a series of tailored N-decorated carbon nanotubes to be employed as chemoselective metal-free electrocatalysts. The choice of an exohedral functionalization tool for the introduction of defined N-groups at the outer surface of carbon nanomaterials warrants a unique control on N-configuration and electronic charge density distribution at the dangling heterocycles. A comparative electrochemical screening of variably N-substituted carbon nanomaterials in CO2RR together with an analysis of the electronic charge density distribution at each heterocycle have suggested the existence of a coherent descriptor for the catalyst’s CO faradaic efficiency (FECO). Evidence allows to infer that N-configuration (N-pyridinic vs. N-pyrrolic) of exohedral dopants and electronic charge density distribution at the N-neighboring carbon atoms of each heterocycle are directly engaged in the activation and stabilization of CO2 and its reduction intermediates.

Dependence of the normal modes on the electronic structure of various phases of ice as calculated by ab initio methods

2003 ◽  
Vol 81 (1-2) ◽  
pp. 225-231 ◽  
Author(s):  
S Jenkins ◽  
S R Kirk ◽  
A S Côté ◽  
D K Ross ◽  
I Morrison
Keyword(s):  
Electronic Structure ◽  
Density Distribution ◽  
Charge Density ◽  
Ab Initio ◽  
Normal Modes ◽  
Cost Effective ◽  
Ab Initio Methods ◽  
Charge Density Distribution ◽  
The Creation

The charge-density distribution in various phases of ice is used to explore the information that can be obtained about the preferred directions of motion of atoms so as to investigate the possibility of the creation of more efficient and computationally cost-effective dynamical matrices. PACS Nos.: 63.20Dj, 31.90+s, 71.10-w

Ab initio Hartree–Fock study of the electronic charge density of the cubic boron nitride and its comparison with experiments

1996 ◽  
Vol 52 (4) ◽  
pp. 586-595 ◽  
Author(s):  
A. Lichanot ◽  
P. Azavant ◽  
U. Pietsch
Keyword(s):  
Charge Transfer ◽  
Boron Nitride ◽  
Charge Density ◽  
Ab Initio ◽  
Cubic Boron Nitride ◽  
Electronic Charge ◽  
Total Density ◽  
Electronic Charge Density ◽  
Acta Cryst ◽  
Hartree Fock

The electronic charge density of cubic boron nitride is calculated within the ab initio Hartree–Fock approximation using the program CRYSTAL. Based on Debye hypothesis, the thermal motion of atoms is considered by disturbing the atomic orbitals by mean-square displacements given from experiment. The calculated difference charge density obtained by subtraction of the total density and that of an independent atomic model (IAM) is characterized by a charge-density accumulation between next neighbours slightly shifted towards the nitrogen. The calculated X-ray structure amplitudes are compared with two different data sets [Josten (1985). Thesis. University of Bonn, Germany; Eichhorn, Kirfel, Grochowski & Serda (1991). Acta Cryst. B47, 843–848]. In both cases, very good agreement is found beyond the 420 reflection. The first six structure amplitudes are generally lower or larger compared with Josten's and Eichhorn et al.'s data, respectively. Whereas our charge density can be interpreted by a balanced ratio between covalent overlap and electronic charge transfer between neighbouring valence shells, the density plots calculated from experimental data express either the charge transfer (Josten, 1985) or the covalency (Eichorn et al., 1991).

Charge Density Study of 2-Pyridone

1998 ◽  
Vol 54 (6) ◽  
pp. 912-920 ◽  
Author(s):  
H. W. Yang ◽  
B. M. Craven
Keyword(s):  
Charge Density ◽  
Critical Points ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Electronic Charge ◽  
Charge Density Distribution ◽  
Electronic Charge Density ◽  
Molecular Dipole ◽  
X Ray ◽  
Density Study

The crystal structure of 2-pyridone has been redetermined from high-resolution X-ray data collected at 123 K. The molecule is in the lactam form. Bond lengths (corrected for rigid-body libration) and angles have been determined with s.u.'s of 0.001 Å and 0.1°, respectively. The hydrogen-bonded cyclic dimers which occur in the vapor and in solution are absent in the crystal where molecules are linked by N—H...O hydrogen bonds to form puckered chains. There also appears to be a weaker C—H...O interaction (H...O, 2.57 Å) and weak C—H...π or van der Waals interactions occurring on both sides of the pyridone ring. Following a refinement of the structure assuming Stewart's rigid pseudo-atom model, the electronic charge density distribution in the crystal and its Laplacian have been calculated for atoms at rest. The total electrostatic potential has been mapped for an isolated molecule and the molecular dipole moment has been determined [8.8 (19)  D; 1D ≃ 3.33564 × 10−30 C m]. Critical points in the electron density have been located for the bonds within the molecule and for the molecular interactions cited above. For the C—H...π interactions, only the spherical components of the valence density for the pyridone ring atoms contribute effectively at the critical points. Hence, these may be better described as van der Waals interactions.

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