Chemisorption of Ordered Overlayer on a Tight-Binding Metal Surface Two-Level Adsorbate

1982 ◽  
Vol 37 (10) ◽  
pp. 1147-1164
Author(s):  
K. Masuda
Keyword(s):  
Phase Shift ◽  
Transition Metal ◽  
Density Of States ◽  
Tight Binding ◽  
Electronic States ◽  
Bridge Site ◽  
Bonding Interaction ◽  
Model Transition ◽  
Adsorbate Structure ◽  
Shift Technique

The chemisorption of a two-level (at E1 and E2) adsorbate on the (001) surface of a tightbinding metal is investigated using the Green's function formalism and the phase shift technique. The adorbital density of states (DOS)ϱa(E) as well as the change in the electronic DOS Δϱ(E; E1, E2) due to chemisorption are calculated for the ordered overlayers with c(2 x 2), p(2 x 1), p(2 X 2), p(4 X 1) and c(4 X 2) structures. It is assumed that the chemisorbed species sit over the twofold bridge site of the (001) surface of the model transition metal and have a π-bonding interaction with the two substrate atoms. It is shown that the electronic states of the overlayers are very sensitive to the adsorbate coverage (0), adsorbate structure and adsorbate species (one level or two level adsorbates). Furthermore, it is shown that there are marked differences in the Δϱ(E) curves between the chemisorption of two level adsorbates Δϱ(E; E1, E2) and that of single level adsorbates Δϱ(E; E1) + Δϱ(E; E2) (simulating the changes in the electronic DOS during the dissociation of diatomic molecules).

Chemisorption on a Model Transition Metal

1976 ◽  
Vol 31 (11) ◽  
pp. 1344-1347 ◽  
Author(s):  
Kin-ichi Masuda
Keyword(s):  
Phase Shift ◽  
Transition Metal ◽  
Density Of States ◽  
Binding Sites ◽  
Steric Effects ◽  
Bridge Site ◽  
Electronic Density ◽  
Electronic Density Of States ◽  
Model Transition ◽  
Shift Technique

Abstract The effect of chemisorption on the (100) surface of a model transition metal is investigated using Green's functions coupled with the phase shift technique. A change in the electronic density of states (DOS) is obtained for two different binding sites, the on-site and the bridge-site; strong steric-effects are present. The importance of the substrate DOS for chemisorption is pointed out.

Changes in Density of States Caused by Chemisorption: Monolayer of Adatoms on a Model Transition Metal

1978 ◽  
Vol 33 (1) ◽  
pp. 66-73
Author(s):  
Kin-ichi Masuda
Keyword(s):  
Electronic Structure ◽  
Phase Shift ◽  
Transition Metal ◽  
Density Of States ◽  
Anderson Model ◽  
Surface Density ◽  
Direct Interaction ◽  
Coverage Dependence ◽  
Model Transition ◽  
Shift Technique

The effect of chemisorption of a monolayer of atoms on the (001) surface of a model transition metal is investigated using the Green's function formalism and the phase shift technique. The electronic structure of the surface is obtained by the application of the Kalkstein and Soven method. For comparison, both a single and two peaked model of the surface density of states (DOS) are used. The change in the DOS upon chemisorption as well as the adatom DOS are calculated within the Newns-Anderson model for chemisorption. It is shown that the two peaked substrate DOS model can qualitatively account for the strong coverage dependence of the photoemission spectra observed in the H/W(100) system. In addition, it is shown that the direct interaction between the adatoms plays an important role in the monolayer chemisorption.

scholarly journals Augmented Space Recursion Method for the Study of Electronic States of Binary Alloys

1970 ◽  
Vol 44 (3) ◽  
pp. 255-264
Author(s):  
M Abdus Salam ◽  
Kabir Ahmed ◽  
BP Barua ◽  
MSI Aziz
Keyword(s):  
Electronic Structure ◽  
Density Of States ◽  
Tight Binding ◽  
Electronic States ◽  
Density Of State ◽  
Recursion Method ◽  
Disordered Alloys ◽  
Lmto Method ◽  
Augmented Space ◽  
Space Formalism

We have studied here the electronic structure of pure random disordered alloys formed by Ni with Cu and Au at different ratios by using the linearized tight-binding muffin-tin Orbital (TB-LMTO) method. We also used the recursion technique together with augmented space formalism for increasing the efficiency and the accuracy to calculate the component projected density of states. From the density of state, we can understand the Fermi energy, magnetic moment and binding energy at different alloy compositions. The band structure can be calculated from here also. These studies are helpful for experimentalists and metallurgists in designing materials and alloys with specific properties. Key words: Electronic structure, Alloys, TB-LMTO, Density of states, Augmented space recursion   DOI: 10.3329/bjsir.v44i3. Bangladesh J. Sci. Ind. Res. 44(3), 255-264, 2009

Transition Metal Impurity-Dislocation Interactions in NiAl: Dislocation Friction and Dislocation Locking

2000 ◽  
Vol 646 ◽  
Author(s):  
O. Yu. Kontsevoi ◽  
Yu.N. Gornostyrev ◽  
A.J. Freeman
Keyword(s):  
Transition Metal ◽  
Central Atom ◽  
Tight Binding ◽  
Electronic States ◽  
Dislocation Core ◽  
Real Space ◽  
Solid Solution Hardening ◽  
Full Potential ◽  
Recursion Method ◽  
Transition Metal Impurity

ABSTRACTThe energetics of the interaction of the <100>{010} edge dislocation in NiAl with early 3d transition metal (TM) impurities was studied using the ab initio real-space tight-binding LMTO-recursion method with 20,000 atom clusters and up to 1,000 non-equivalent atoms in the dislocation core. The coordinates of the atoms in the core were determined within the Peierls-Nabarro (PN) model with restoring forces determined from full-potential LMTO total energy calculations. TM impurities were then placed in different substitutional positions near the dislocation core. For most positions studied, the interaction between impurities and the dislocation is found to be repulsive (dislocation friction). However, when the impurity is in the position close to the central atom of the dislocation core, the interaction becomes strongly attractive, thus causing dislocation locking. Since the size misfit between the Al atom and the substituting TM atom is very small, this locking cannot be explained by elastic (or size misfit) mechanisms; it has an electronic nature and is caused by the formation of the preferred bonding between the electronic states of the impurity atom and the localized electronic states appearing on the central atom of the dislocation core. The calculated results are then discussed in the scope of experimental data on solid solution hardening in NiAl.

Magnetic Volume Effect of Hydrogen Diffusion in Palladium

2020 ◽  
Vol 310 ◽  
pp. 29-33
Author(s):  
Sarantuya Nasantogtokh ◽  
Xin Cui ◽  
Zhi Ping Wang
Keyword(s):  
Transition Metal ◽  
Density Of States ◽  
Density Functional ◽  
Hydrogen Diffusion ◽  
Magnetic Moments ◽  
Interstitial Site ◽  
Volume Effect ◽  
Face Centered Cubic ◽  
Hydrogen Atoms ◽  
Octahedral Interstitial Site

The electronic and magnetic properties of palladium hydrogen are investigated using first-principles spin-polarized density functional theory. By studying the magnetic moments and electronic structures of hydrogen atoms diffusing in face-centered cubic structure of transition metal Pd, we found that the results of magnetic moments are exactly the same in the two direct octahedral interstitial site-octahedral interstitial site diffusion paths-i.e. the magnetic moments are the largest in the octahedral interstitial site, and the magnetic moments are the lowest in saddle point positions. We also studied on the density of states of some special points, with the result that the density of states near the Fermi level is mainly contributed by 4d electrons of Pd and the change of magnetic moments with the cell volume in the unit cell of transition metal Pd with a hydrogen atom.

scholarly journals Single-crystalline epitaxial TiO film: A metal and superconductor, similar to Ti metal

2021 ◽  
Vol 7 (2) ◽  
pp. eabd4248
Author(s):  
Fengmiao Li ◽  
Yuting Zou ◽  
Myung-Geun Han ◽  
Kateryna Foyevtsova ◽  
Hyungki Shin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Tight Binding ◽  
Crystal Form ◽  
Titanium Monoxide ◽  
Binding Model ◽  
Functional Theory ◽  
Single Crystalline ◽  
First Time ◽  
Lattice Matched

Titanium monoxide (TiO), an important member of the rock salt 3d transition-metal monoxides, has not been studied in the stoichiometric single-crystal form. It has been challenging to prepare stoichiometric TiO due to the highly reactive Ti2+. We adapt a closely lattice-matched MgO(001) substrate and report the successful growth of single-crystalline TiO(001) film using molecular beam epitaxy. This enables a first-time study of stoichiometric TiO thin films, showing that TiO is metal but in proximity to Mott insulating state. We observe a transition to the superconducting phase below 0.5 K close to that of Ti metal. Density functional theory (DFT) and a DFT-based tight-binding model demonstrate the extreme importance of direct Ti–Ti bonding in TiO, suggesting that similar superconductivity exists in TiO and Ti metal. Our work introduces the new concept that TiO behaves more similar to its metal counterpart, distinguishing it from other 3d transition-metal monoxides.

scholarly journals The Effect of Iron Impurities on Transition Metal Catalysts for the Oxygen Evolution Reaction in Alkaline Environment: Activity Mediators or Active Sites?

2020 ◽  
Author(s):  
Ioannis Spanos ◽  
Justus Masa ◽  
Aleksandar Zeradjanin ◽  
Robert Schlögl
Keyword(s):  
Transition Metal ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Water Electrolysis ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Alkaline Water Electrolysis ◽  
Co Catalysts ◽  
Model Transition

AbstractThere is an ongoing debate on elucidating the actual role of Fe impurities in alkaline water electrolysis, acting either as reactivity mediators or as co-catalysts through synergistic interaction with the main catalyst material. This perspective summarizes the most prominent oxygen evolution reaction (OER) mechanisms mostly for Ni-based oxides as model transition metal catalysts and highlights the effect of Fe incorporation on the catalyst surface in the form of impurities originating from the electrolyte or co-precipitated in the catalyst lattice, in modulating the OER reaction kinetics, mechanism and stability. Graphic Abstract

Phase Shift Technique to Improve Torque of Synchronous Reluctance Machines With Dual M-Phase Windings

2021 ◽  
pp. 1-1
Author(s):  
Wenxiang Zhao ◽  
Yuhua Sun ◽  
Jinghua Ji ◽  
Zhujin Ren ◽  
Xinxin Song
Keyword(s):  
Phase Shift ◽  
M Phase ◽  
Shift Technique
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