Surface Diffusion and Incorporation Process of Adatom in Fe-Al Multilayer System

2006 ◽  
Vol 317-318 ◽  
pp. 411-414 ◽  
Author(s):  
Chi Ho Kim ◽  
In Yong Kang ◽  
Yong Chae Chung
Keyword(s):  
Total Energy ◽  
Ab Initio ◽  
Surface Diffusion ◽  
Energy Barrier ◽  
Energy Gain ◽  
Multilayer System ◽  
Large Energy ◽  
Hollow Site ◽  
Pseudopotential Calculations ◽  
Adsorption Energies

Using the ab initio pseudopotential calculations, the surface diffusion and incorporation process at the interface of Fe-Al multilayer system were quantitatively investigated. The hollow site was most stable adsorption site on both Al (001) and Fe (001) surface. The adsorption energies were 8.62 eV for Fe/Al (001) and 5.30 eV for Al/Fe (001) system. The calculated energy barriers for the surface diffusion of adatom were 0.89 eV and 0.61 eV for each system. The energy barrier for the incorporation of Fe adatom into the Al substrate was calculated to be 0.38 eV and the energy gain of the system was 0.49 eV. However, the Al adatom required relatively large energy barrier, 0.99 eV for the incorporation into the Fe substrate resulting in 0.13 eV increase in total energy of the system.

Calculations of SiH3 Diffusion and Growth Processes on a-Si:H Surfaces

2003 ◽  
Vol 762 ◽  
Author(s):  
P Vigneron ◽  
P W Peacock ◽  
K Xiong ◽  
J Robertson
Keyword(s):  
Total Energy ◽  
Amorphous Silicon ◽  
Surface Diffusion ◽  
Bound States ◽  
Smooth Surface ◽  
Hydrogenated Amorphous Silicon ◽  
Weakly Bound ◽  
Growth Site ◽  
Pseudopotential Calculations ◽  
Hydrogenated Amorphous

AbstractSurface diffusion of a growth species is needed to give the observed smooth surface of hydrogenated amorphous silicon (a-Si:H). But what diffuses, the weakly bound SiH3 radical on the hydrogenated surface, or the bound SiH3 at a growth site. Diffusion is complicated by the change in the surface termination of a-Si:H as temperature rises. We use total energy pseudopotential calculations on a variety of periodic Si:H surface configurations to show that it is the weakly bound SiH3 that diffuses. We provide an overall energy scheme of the bound states and transport levels of SiH3 on a-Si:H surfaces.

AB INITIO STUDY OF MAGNETISM IN PALLADIUM CLUSTERS SUPPORTED ON (110) SURFACE OF TiO2 RUTILE

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2544-2549 ◽  
Author(s):  
P. MURUGAN ◽  
VIJAY KUMAR ◽  
YOSHIYUKI KAWAZOE
Keyword(s):  
Ab Initio ◽  
Magnetic Moments ◽  
High Mobility ◽  
Oxide Surface ◽  
Generalized Gradient ◽  
Palladium Clusters ◽  
Atomic Structures ◽  
Pseudopotential Calculations ◽  
Adsorption Energies ◽  
Tio2 Rutile

The structural, electronic, and magnetic properties of Pd n (n = 6, 13) clusters supported on (110) surface of TiO 2 rutile have been studied using ab initio ultrasoft pseudopotential calculations within generalized gradient approximation. The magnetic moments and atomic structures of these clusters have only small changes when soft landed on the oxide surface. The magnetic moments of Pd 13 cluster on TiO 2 (110) surface is reduced to 6 μB as compared to 8 μB for free cluster. Our calculations also show that the adsorption energy differences between various orientations of Pd 13 cluster on the surface of the slab are small. Therefore, nearly spherical clusters such as Pd 13 can roll and have high mobility. The calculated adsorption energies of Pd 6 and Pd 13 on the (110) surface of TiO 2 slab are approximately 2.2 and 2.4 eV, respectively.

Ab Initio Investigation of Grain Boundary Sliding

1995 ◽  
Vol 408 ◽  
Author(s):  
M. C. Payne ◽  
G. P. Francis ◽  
C. Molteni ◽  
N. Marzari ◽  
V. Deyirmenjian ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Total Energy ◽  
Ab Initio ◽  
Grain Boundary Sliding ◽  
Microscopic Level ◽  
Extensive Investigation ◽  
Preliminary Results ◽  
Pseudopotential Calculations ◽  
Covalently Bonded ◽  
Boundary Sliding

AbstractWe are using total energy pseudopotential calculations to carry out an extensive investigation into grain boundary sliding in a number of different systems, in order to understand, at microscopic level, the fundamental mechanisms responsible for this process.In this paper we present results for the sliding process at the ∑ = 5(001) twist grain boundary in germanium, chosen as a typical covalently bonded material, and contrast them with preliminary results obtained for the ∑ = 5 (001) twist grain boundary in aluminium, a typical metal.

Ab initio band theory approach to electron energy loss near edge structures

1988 ◽  
Vol 46 ◽  
pp. 506-507
Author(s):  
Xudong Weng ◽  
O.F. Sankey ◽  
Peter Rez
Keyword(s):  
Ab Initio ◽  
Local Density ◽  
Interpolation Method ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Large Set ◽  
Theory Approach ◽  
Band Theory ◽  
Atomic Orbitals ◽  
Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

Exchange-Biasing in a Dinuclear Dysprosium(III) Single-Molecule Magnet with a Large Energy Barrier for Magnetization Reversal

2019 ◽  
Author(s):  
Tian Han ◽  
Marcus J. Giansiracusa ◽  
Zi-Han Li ◽  
You-Song Ding ◽  
Nicholas F. Chilton ◽  
...  
Keyword(s):  
Single Molecule ◽  
Magnetization Reversal ◽  
Energy Barrier ◽  
Magnetic Hysteresis ◽  
Large Energy ◽  
Magnetic Studies ◽  
Bridging Ligands ◽  
Single Molecule Magnet ◽  
Exchange Biasing

A dichlorido-bridged dinuclear dysprosium(III) single-molecule magnet [Dy<sub>2</sub>L<sub>2</sub>(<i>µ</i>-Cl)<sub>2</sub>(THF)<sub>2</sub>] has been made using a diamine-bis(phenolate) ligand, H<sub>2</sub>L. Magnetic studies show an energy barrier for magnetization reversal (<i>U</i><sub>eff</sub>) around 1000 K. Exchange-biasing effect is clearly seen in magnetic hysteresis with steps up to 4 K. <i>Ab</i> initio calculations exclude the possibility of pure dipolar origin of this effect leading to the conclusion that super-exchange <i>via</i> the chloride bridging ligands is important.

scholarly journals A dichlorido-bridged dinuclear Dy(iii) single-molecule magnet with an effective energy barrier larger than 600 K

2019 ◽  
Vol 55 (55) ◽  
pp. 7930-7933 ◽  
Author(s):  
Tian Han ◽  
You-Song Ding ◽  
Zi-Han Li ◽  
Ke-Xin Yu ◽  
Yuan-Qi Zhai ◽  
...  
Keyword(s):  
Single Molecule ◽  
Magnetization Reversal ◽  
Energy Barrier ◽  
Large Energy ◽  
Effective Energy ◽  
Single Molecule Magnet

A large energy barrier for magnetization reversal of about 623 K is observed in a dichlorido-bridged Dy(iii) dimer.

Effect of Chromium and Vanadium on Nanolayered Ternary Carbides: AB Initio Study

2009 ◽  
Vol 609 ◽  
pp. 239-242
Author(s):  
A.E. Merad ◽  
M.B. Kanoun
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Ab Initio ◽  
Structural Parameters ◽  
Ab Initio Study ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Full Relaxation ◽  
Relaxation Procedure ◽  
Ternary Carbides

The Cr2AlC and V2AlC nanolayered ternary carbides are studied by performing APW-lo ab initio total energy calculations within the recent Wu-Cohen generalized gradient approximation GGA. Using full relaxation procedure of the volume and the atomic positions we obtained the structural parameters and electronic structure of the optimization hexagonal. Results were compared with the experimental ones. Interesting features are deduced. In fact, we have shown why these materials are conductors.

Ab Initio Computation of Thermochemistry and Kinetics in the Oxidation of Gas Phase Silicon Species

1992 ◽  
Vol 282 ◽  
Author(s):  
Michael R. Zachariah ◽  
Wing Tsang
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Energy Barrier ◽  
Reaction Rate ◽  
Rate Theory ◽  
Molecular Orbital Calculations ◽  
Activation Energy Barrier ◽  
Ab Initio Computation ◽  
Oxygen Donor ◽  
Reaction Rate Theory

ABSTRACTAb initio molecular orbital calculations coupled to RRKM reaction rate theory have been conducted on some important reactions involved in the oxidation of silane in a high-temperature/high H2O environment. The results indicate thatH2O acts as an oxygen donor to SiH2 to form H3SiOH or SiH2O. Subsequent reactions involve the formation of (HSiOOH, H2Si(OH)2,:Si(OH)2 or SiO). In turn SiO polymerizes into planar rings, without an activation energy barrier. A list of calculated thermochemical data are also presented for a number of equilibrium species.

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