First Principles Study of Hydrogen Adsorption and Diffusion on Transition Metal Surfaces: Application to the Ru (0001) Surface

1988 ◽  
Vol 141 ◽  
Author(s):  
James R. Chelikowsky-al ◽  
M.-Y. Chou
Keyword(s):  
First Principles ◽  
Hydrogen Diffusion ◽  
Potential Surface ◽  
Hydrogen Adsorption ◽  
Activation Barrier ◽  
Local Density ◽  
Density Approximation ◽  
Good Accord ◽  
Adsorption Energies ◽  
And Diffusion

AbstractHydrogen adsorption and diffusion on the (0001) surface of ruthenium is investigated using ab initio pseudopotentials within the local density approximation. The adsorption energies at a number of different sites and bond lengths were investigated via total energy calculations. Using these calculated values a potential surface was constructed and an estimate for the activation barrier for hydrogen diffusion was obtained. The calculated value of 4.0 kcal is in good accord with the value of ≈ 4 kcal as determined from laser-induced thermal desorption experiments.

scholarly journals First-Principles Investigation of Atomic Hydrogen Adsorption and Diffusion on/into Mo-doped Nb (100) Surface

2018 ◽  
Vol 8 (12) ◽  
pp. 2466 ◽  
Author(s):  
Yang Wu ◽  
Zhongmin Wang ◽  
Dianhui Wang ◽  
Jiayao Qin ◽  
Zhenzhen Wan ◽  
...  
Keyword(s):  
First Principles ◽  
Atomic Hydrogen ◽  
Energy Barrier ◽  
Hydrogen Adsorption ◽  
Hydrogen Permeation ◽  
Diffusion Path ◽  
Interstitial Site ◽  
Octahedral Interstitial Site ◽  
Tetrahedral Interstitial Site ◽  
And Diffusion

To investigate Mo doping effects on the hydrogen permeation performance of Nb membranes, we study the most likely process of atomic hydrogen adsorption and diffusion on/into Mo-doped Nb (100) surface/subsurface (in the Nb12Mo4 case) via first-principles calculations. Our results reveal that the (100) surface is the most stable Mo-doped Nb surface with the smallest surface energy (2.75 J/m2). Hollow sites (HSs) in the Mo-doped Nb (100) surface are H-adsorption-favorable mainly due to their large adsorption energy (−4.27 eV), and the H-diffusion path should preferentially be HS→TIS (tetrahedral interstitial site) over HS→OIS (octahedral interstitial site) because of the correspondingly lower H-diffusion energy barrier. With respect to a pure Nb (100) surface, the Mo-doped Nb (100) surface has a smaller energy barrier along the HS→TIS pathway (0.31 eV).

scholarly journals First-Principles Determination of the Polarizabilities of Carbon Tubules as a Function of Length

1994 ◽  
Vol 349 ◽  
Author(s):  
Andrew A. Quong ◽  
Mark R. Pederson
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Valence Electron ◽  
Local Density ◽  
Density Approximation ◽  
Functional Theory ◽  
Size Dependent ◽  
The Density Functional Theory ◽  
Linear And Nonlinear

ABSTRACTWe use the local-density-approximation to the density-functional theory to determine the axial polarizabilities of fullerene tubules as a function of length and winding topologies. Specifically, we present linear polarizabilities for tubules of composition C12H24, C36H24, C40H20 and C60H24. The size-dependent variation in the dipole-coupled gaps between pairs of occupied and unoccupied levels leads to enhancements in the polarizability per valence electron as the length of the tubule increases. The results are compared to recent densityfunctional based calculations of the linear and nonlinear polarizabilities for fullerene and benzene molecules.

A First-Principles Study of Pd-Pt Nanoclusters and their Hydrogen Adsorption Properties

2012 ◽  
Vol 1446 ◽  
Author(s):  
Teck L. Tan ◽  
Kewu Bai
Keyword(s):  
Particle Size ◽  
First Principles ◽  
Hydrogen Adsorption ◽  
Surface Adsorption ◽  
Expansion Method ◽  
Pt Nanoclusters ◽  
Cluster Expansion Method ◽  
Pt Alloy ◽  
Effect Of Particle Size ◽  
Adsorption Energies

ABSTRACTTo demonstrate the effects of particle size and alloying on hydrogen adsorption on metals, we explore stable configurations of Pd-Pt alloy using a 55-atom cubo-octahedron. Via first-principles based cluster expansion method, we obtained groundstate configurations and show how their hydrogen adsorption energies change with Pd-Pt composition. Comparison with surface adsorption energies further shows the effect of particle size.

First-principles Calculations of Energetic Properties of Vacancies, Mn-atomic Defects in CdTe

2006 ◽  
Vol 959 ◽  
Author(s):  
Ghouti Merad ◽  
Benali Rerbal ◽  
Hafid Aourag ◽  
Joël Cibert
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Density Approximation ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Energetic Properties ◽  
Atomistic Modelling ◽  
Atomic Type

ABSTRACTAn atomistic modelling based on density functional theory within the framework of the local density approximation is used to show the trends in the energetic properties of single and double defects in CdTe semiconductor, without phase transformation. A systematic study of vacancies, Mn substituting Cd atoms in a supercell structure consisting of 16-atoms is presented. The changes of structural properties and lattice parameters due to the addition of Mn-atomic type defects in CdTe matrix are compared, and the number of vacancies is also determined from the total energy calculations.

First Principles Calculations of Surface Stress

1988 ◽  
Vol 141 ◽  
Author(s):  
Robert D. Meade ◽  
David Vanderbilt
Keyword(s):  
First Principles ◽  
Surface Stress ◽  
Local Density ◽  
Quantum Mechanical ◽  
Density Approximation ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Basis Size ◽  
Total Energies ◽  
Dimensional Surface

AbstractOnly recently have there been fully quantum-mechanical calculations of two-dimensional surface stress tensors. We have calculated total energies and stresses of semiconductor surfaces within the Local Density Approximation, using norm-conserving pseudopotentials. In order to hasten convergence of the stress with respect to basis size, it is useful to remove a fictitious tensile stress. We have calculated surface stress for the relaxed Si (111) 1×1 and 2×2-adatom surfaces, as well as for the relaxed Ge (111) 1×1 and 2×2-adatom surfaces. We have also calculated the surface stress for several chemisorbed systems, including Ga, Ge and As chemisorbed onto Si. We find a dramatic correlation between the electronic structure and chemistry of the surface, and its elastic properties.

Ab initio calculations of the magnetic properties of TM (Ti, V)-doped zinc-blende ZnO

2018 ◽  
Vol 32 (03) ◽  
pp. 1850025 ◽  
Author(s):  
F. Goumrhar ◽  
L. Bahmad ◽  
O. Mounkachi ◽  
A. Benyoussef
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Exchange Coupling ◽  
Local Density ◽  
Density Approximation ◽  
Potential Approximation ◽  
Half Metallic ◽  
Suitable Material ◽  
Zinc Blende ◽  
Exchange Coupling Interaction

In order to promote suitable material to be used in spintronics devices, this study purposes to evaluate the magnetic properties of the titanium and vanadium-doped zinc-blende ZnO from first-principles. The calculations of these properties are based on the Korringa–Kohn–Rostoker (KKR) method combined with the coherent potential approximation (CPA), using the local density approximation (LDA). We have calculated and discussed the density of states (DOSs) in the energy phase diagrams for different concentration values, of the dopants. We have also investigated the magnetic and half-metallic properties of this doped compound. Additionally, we showed the mechanism of the exchange coupling interaction. Finally, we estimated and studied the Curie temperature for different concentrations.

Possible Ferroelectricity in SnTiO3 by First-Principles Calculations

2002 ◽  
Vol 748 ◽  
Author(s):  
Yoshinori Konishi ◽  
Michio Ohsawa ◽  
Yoshiyuki Yonezawa ◽  
Yoshiya Tanimura ◽  
Toyohiro Chikyow ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Spontaneous Polarization ◽  
First Principles ◽  
Local Density Approximation ◽  
Lattice Structure ◽  
Local Density ◽  
Density Approximation ◽  
First Principles Calculations ◽  
Minimum Total Energy ◽  
The Moment

ABSTRACTThe prospect of lattice structure and ferroelectricity of SnTiO3 have been studied by first-principles calculations within local density approximation. The results showed that the SnTiO3 has the minimum total energy within almost tetragonal perovskite structure of a=b=3.80 Å, c=4.09 Å. The calculated electronic structure of SnTiO3 resembles that of PbTiO3 because the Ti 3d states, Sn 5s and 5p states hybridize with the O 2p orbitals. The moment of spontaneous polarization of SnTiO3 was estimated as 73 μ C/cm2, which is as large as that of PbTiO3.

Hydrogen Adsorption and Diffusion on the Anatase TiO2(101) Surface: A First-Principles Investigation

2011 ◽  
Vol 115 (14) ◽  
pp. 6809-6814 ◽  
Author(s):  
Mazharul M. Islam ◽  
Monica Calatayud ◽  
Gianfranco Pacchioni
Keyword(s):  
First Principles ◽  
Hydrogen Adsorption ◽  
Anatase Tio2 ◽  
And Diffusion
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