Dependence of stability, bond strength and electronic structure of dimetal units upon atomic number, oxidation number and chemical environment

1980 ◽  
Vol 14 ◽  
pp. 180 ◽  
Author(s):  
Bruce E. Bursten ◽  
F. Albert Cotton
Keyword(s):  
Electronic Structure ◽  
Bond Strength ◽  
Atomic Number ◽  
Chemical Environment ◽  
Oxidation Number ◽  
Dimetal Units

Electronic structure and chemical environment of silicon nanoclusters embedded in a silicon dioxide matrix

2006 ◽  
Vol 88 (16) ◽  
pp. 163103 ◽  
Author(s):  
Anna Zimina ◽  
Stefan Eisebitt ◽  
Wolfgang Eberhardt ◽  
Johannes Heitmann ◽  
Margit Zacharias
Keyword(s):  
Electronic Structure ◽  
Silicon Dioxide ◽  
Chemical Environment ◽  
Silicon Nanoclusters ◽  
Silicon Dioxide Matrix

THE EFFECT OF 3dn IMPURITIES IN THE YBa2Cu3O7−δ SUPERCONDUCTOR

1993 ◽  
Vol 07 (22) ◽  
pp. 1449-1456
Author(s):  
G. A. R. LIMA ◽  
VITOR TORRES ◽  
A. FAZZIO
Keyword(s):  
Electronic Structure ◽  
Transition Metal ◽  
Atomic Number ◽  
Configuration Interaction ◽  
Narrow Band ◽  
Correlation Effects ◽  
Chemical Trends

The electronic structure of the CuO chain and the CuO 2 plane in the superconductor YBa 2 Cu 3 O 7−δ doped with 3dn transition-metal (TM) atoms are investigated. The calculations were performed through the semiempirical INDO/S technique, where the correlation effects are taken into account by the Configuration Interaction (CI) procedure. We also calculated, for all 3dn impurities, the Hubbard parameters Udd corresponding to a narrow band. The results obtained demonstrate clear chemical trends in the electronic structure of the 3d's, from Ti to Ni, when they substitute Cu(1) and Cu(2) sites; the hybridization decreases when the atomic number Z decreases. Our work provides a picture which is important to understand the change in T c when the host is doped with TM atom.

scholarly journals Effect of the Free Volume on the Electronic Structure of Cu70Zr30 Metallic Glasses

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4911
Author(s):  
Simon Evertz ◽  
Jochen M. Schneider
Keyword(s):  
Electronic Structure ◽  
Bond Strength ◽  
Coordination Number ◽  
Free Volume ◽  
Metallic Glasses ◽  
Volume Content ◽  
Short Distance ◽  
Volume Fraction ◽  
Plastic Behavior ◽  
Local Bonding

While it is accepted that the plastic behavior of metallic glasses is affected by their free volume content, the effect on chemical bonding has not been investigated systematically. According to electronic structure analysis, the overall bond strength is not significantly affected by the free volume content. However, with an increasing free volume content, the average coordination number decreases. Furthermore, the volume fraction of regions containing atoms with a lower coordination number increases. As the local bonding character changes from bonding to anti-bonding with a decreasing coordination number, bonding is weakened in the volume fraction of a lower coordination number. During deformation, the number of strong, short-distance bonds decreases more for free volume-containing samples than for samples without free volume, resulting in additional bond weakening. Therefore, we show that the introduction of free volume causes the formation of volume fractions of a lower coordination number, resulting in weaker bonding, and propose that this is the electronic structure origin of the enhanced plastic behavior reported for glasses containing free volume.

scholarly journals Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi2Se3

2017 ◽  
Vol 407 ◽  
pp. 371-378 ◽  
Author(s):  
Turgut Yilmaz ◽  
William Hines ◽  
Fu-Chang Sun ◽  
Ivo Pletikosić ◽  
Joseph Budnick ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Topological Insulator ◽  
Chemical Environment ◽  
Surface Deposition

scholarly journals Inclusion of Relativistic Effects in Electronic Structure Calculations

1986 ◽  
Vol 39 (5) ◽  
pp. 667 ◽  
Author(s):  
KG Dyall
Keyword(s):  
Molecular Structure ◽  
Electronic Structure ◽  
Dirac Equation ◽  
Atomic Number ◽  
Perturbation Methods ◽  
Relativistic Effects ◽  
Electronic Structure Calculations ◽  
Variational Treatment ◽  
Structure Calculations

The effects of relativity on atomic and molecular structure are discussed with an indication of their importance as a function of atomic number. Perturbation methods for the inclusion of relativistic effects are briefly analysed in terms of the Dirac equation; the multi-configuration Dirac-Fock method for the variational treatment of relativistic effects is then discussed in more detail. Finally, a case study on 2p ionisation in Ca is presented, in which higher-order relativistic effects are important.

Sulfur bonding in cyclic P2S2N4 systems: a density functional comparison of 1,1,5,5-tetramethylbicyclo[3.3.0]-1,5-diphospha-3,7-dithia-2,4,6,8-tetrazocine with the 1,1,3,5,5-pentamethyl-1,5-diphospha-3,7-dithia-2,4,6,8-tetrazocine anion

1994 ◽  
Vol 72 (6) ◽  
pp. 1582-1586 ◽  
Author(s):  
Heiko Jacobsen ◽  
Tom Ziegler ◽  
Tristram Chivers ◽  
Rainer Vollmerhaus
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Bond Strength ◽  
Sulfur Atom ◽  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Density Approximation ◽  
Functional Theory ◽  
Sulfur Bond

The electronic structure and the bonding of the title compounds have been investigated using density functional theory within the local density approximation, adding nonlocal corrections to exchange and correlation energy. The çross-ring sulfur-sulfur bond energy in 1,1,5,5-tetramethylbicyclo[3.3.0]-1,5-diphospha-3,7-dithia-2,4,6,8-tetrazocine was estimated to be about 133 kJ/mol. The HOMO of the 1,1,3,5,5-pentamethyl-1,5-diphospha-3,7-dithia-2,4,6,8-tetrazocine anion is mainly localized at the site of the unmethylated sulfur atom and is antibonding with respect to the sulfur—carbon bond of the methylated sulfur atom, which has a relatively weak estimated bond strength of 218 kJ/mol.

First principles study of influence of alloying elements on TiAl: Lattice distortion

1999 ◽  
Vol 14 (7) ◽  
pp. 2824-2829 ◽  
Author(s):  
Y. Song ◽  
R. Yang ◽  
D. Li ◽  
W. T. Wu ◽  
Z. X. Guo
Keyword(s):  
Electronic Structure ◽  
Bond Strength ◽  
Density Of States ◽  
First Principles ◽  
Lattice Distortion ◽  
Alloying Elements ◽  
Cluster Method ◽  
Partial Density ◽  
Ternary Additions ◽  
The Individual

The influence of ternary additions Cr, Fe, Mn, Ni, Zr, Nb, Mo, Hf, Ta, Si, Ga, Ge, In, and Sb, as well as the anti-site defects of both Ti and Al, on lattice parameters of TiAl were studied by the first principles electronic structure calculations with a discrete variational cluster method. The results of the calculation show that the effect of ternary additions on the distortion of TiAl lattice varies with the substitution behavior of the individual alloying element involved. The addition of alloying elements in TiAl causes a change in the electronic structure and the density of states of the system and results in variation of the bond strength between the atoms. The total and partial density of states (DOS) of binary TiAl and of ternary TiAl–M, M = Cr, Zr, and Sb, etc., were comparatively examined. The relationship between the DOS and the bond strength is discussed. The present work suggests that the origin of the lattice distortion of the ternary TiAl–M systems lies in the variation of the electronic structure.

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