Oxygen vacancy defects in tantalum pentoxide: a density functional study

2002 ◽  
Vol 745 ◽  
Author(s):  
R. Ramprasad ◽  
Michael Sadd ◽  
Doug Roberts ◽  
Tom Remmel ◽  
Mark Raymond ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Chemical Potential ◽  
Orthorhombic Phase ◽  
Functional Study ◽  
Vacancy Defects ◽  
Plane Type ◽  
Study Results ◽  
Wide Range ◽  
Very High

ABSTRACTFirst principles total energy calculations were performed in order to characterize O vacancy defects in Ta2O5. A simplified version of the crystalline orthorhombic phase of Ta2O5 was used in this study. Results indicate that O vacancies in Ta2O5 can be broadly classified based on their location in the lattice. One type of vacancies (occupying the “in-plane” sites) displays deep or mid gap occupied states, and shallow unoccupied states, while a second type (occupying “cap” sites) results in shallow occupied states. For a wide range of local Fermi level or chemical potential, the neutral and +2 charged states of the in-plane type vacancy and the +2 charge state of the cap type vacancy are found to be most stable. Migration energies of the two types of vacancies in the neutral and +2 charge states are markedly different, with the “cap” type of vacancies displaying very high barriers to migration (∼ 5 eV) compared to the “in-plane” type (∼ 0.5–1.0 eV).

Oxygen vacancy defects in tantalum pentoxide: a density functional study

2002 ◽  
Vol 747 ◽  
Author(s):  
R. Ramprasad ◽  
Michael Sadd ◽  
Doug Roberts ◽  
Tom Remmel ◽  
Mark Raymond ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Chemical Potential ◽  
Orthorhombic Phase ◽  
Functional Study ◽  
Vacancy Defects ◽  
Plane Type ◽  
Study Results ◽  
Wide Range ◽  
Very High

ABSTRACTFirst principles total energy calculations were performed in order to characterize O vacancy defects in Ta2O5. A simplified version of the crystalline orthorhombic phase of Ta2O5 was used in this study. Results indicate that O vacancies in Ta2O5 can be broadly classified based on their location in the lattice. One type of vacancies (occupying the “in-plane” sites) displays deep or mid gap occupied states, and shallow unoccupied states, while a second type (occupying “cap” sites) results in shallow occupied states. For a wide range of local Fermi level or chemical potential, the neutral and +2 charged states of the in-plane type vacancy and the +2 charge state of the cap type vacancy are found to be most stable. Migration energies of the two types of vacancies in the neutral and +2 charge states are markedly different, with the “cap” type of vacancies displaying very high barriers to migration (∼ 5 eV) compared to the “in-plane” type (∼ 0.5–1.0 eV).

ELECTRONIC STRUCTURES AND THE STABILITY OF MgO SURFACE: DENSITY FUNCTIONAL STUDY

2015 ◽  
Vol 22 (03) ◽  
pp. 1550037 ◽  
Author(s):  
DIAN-NA ZHANG ◽  
LI ZHAO ◽  
JIA-FU WANG ◽  
YAN-LI LI
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Chemical Potential ◽  
Surface States ◽  
Functional Study ◽  
Functional Theory ◽  
Calculation Results ◽  
The Stability ◽  
Mgo Surface

The electronic structures and the stability of the low-index surface (001), (011) and (111) for MgO were investigated by first-principles method based on density functional theory (DFT). We analyzed the stability of the MgO slab in equilibrium with an arbitrary oxygen environment. The density of states (DOS) and the band structures of MgO slabs were calculated and compared with those of the bulk MgO . Our calculation results reveal that the stabilities of the surface vary with the change of O chemical potential. In addition, the (001) and (011) surfaces are semiconductors, which are similar to that of the bulk MgO . However, the MgO (111) surface exhibits metallic property due to the effect of the surface states, which is different from that of the bulk MgO .

First-Principles Studies of the Magnetic Properties of hcp Cr in Cr/Cu(111) and Cr/Ru(0001) Superlattices

2002 ◽  
Vol 721 ◽  
Author(s):  
G. Y. Guo
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Recent Observation ◽  
Theoretical Calculations ◽  
Ferromagnetic State ◽  
Full Potential ◽  
Generalized Gradient ◽  
Plane Wave Method ◽  
Wide Range ◽  
Linearized Augmented Plane Wave

AbstractLatest first-principles density functional theoretical calculations using the generalized gradient approximation and highly accurate all-eleectron full-potential linearized augmented plane wave method, show that bulk hcp Cr would be a paramagnet and that no ferromagnetic state could be stabilized over a wide range of volume [1]. To understand the recent observation of the weakly ferromagnetic state of Cr in hcp Cr/Ru (0001) superlattices [2], the same theoretical calculations have been carried out for the hcp Cr3/Ru7 (0001) and hcp Cr3/fcc Cu6 (111) superlattices. The Cr/Ru superlattice is found to be ferromagnetic with a small magnetic moment of ∼0.31μB/Cr while in contrast, Cr/Cu superlattice is found to be nonmagnetic.

2-Chlorophenol adsorption on Cu(100): First-principles density functional study

2008 ◽  
Vol 602 (8) ◽  
pp. 1554-1562 ◽  
Author(s):  
Mohammednoor Altarawneh ◽  
Marian W. Radny ◽  
Phillip V. Smith ◽  
John C. Mackie ◽  
Eric M. Kennedy ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Functional Study ◽  
Density Functional Study

First-Principles Study of Interaction of Lithium Atoms with (3, 3) Carbon Nanotubes

2014 ◽  
Vol 687-691 ◽  
pp. 4311-4314 ◽  
Author(s):  
Shun Fu Xu ◽  
Ling Min Li
Keyword(s):  
Carbon Nanotubes ◽  
First Principles ◽  
Density Functional ◽  
Vacancy Defect ◽  
Single Wall Carbon Nanotubes ◽  
Generalized Gradient ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Vacancy Defects ◽  
Adsorption Mechanisms

In this paper, we have employed first-principles calculations to investigate the adsorption mechanisms of one lithium atom on the sidewalls of 1/2/3 H-adsorbed indefective/defective (3, 3) single-wall carbon nanotubes (CNTs) which have vacancy defects. Our calculations are performed within density functional theory (DFT) under the generalized gradient approximation (GGA) of Perdew, Burke, and Ernzerhof (PBE).Our results show that the lithium atoms strongly binds to the H-adsorbed (3, 3) nanotube. Lithium atoms can chemically adsorb on (3, 3) nanotube with the vacancy defect (MVD) without any energy barrier. The lithium adsorption will enhance the electrical conductivity of the nanotube. Further more, the structure of the (3, 3) nanotube with the MVD and hydrogen atoms will become more stable after the three kinds of lithium adsorption.

Effect of Zn2+/Zn layer on H2 dissociation on Ruthenium (0001) surface: A first principles density functional study

2007 ◽  
Vol 807 (1-3) ◽  
pp. 185-189 ◽  
Author(s):  
Pei-Qing Yuan ◽  
Yue-Ming Ma ◽  
Zhen-Min Cheng ◽  
Yi-An Zhu ◽  
Wei-Kang Yuan
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Functional Study ◽  
Density Functional Study

Adsorptions and diffusions of carbon atoms on the surface and in the subsurface of Co (200): A first-principles density-functional study

2014 ◽  
Vol 23 (8) ◽  
pp. 086802
Author(s):  
Liang Qiao ◽  
Shu-Min Wang ◽  
Xiao-Ming Zhang ◽  
Xiao-Ying Hu ◽  
Yi Zeng ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Functional Study ◽  
Density Functional Study

First-Principles Study of TiC(111) Surface

2012 ◽  
Vol 229-231 ◽  
pp. 82-86 ◽  
Author(s):  
Li Wang ◽  
Teng Fang ◽  
Jian Hong Gong
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Chemical Potential ◽  
Charge Accumulation ◽  
Ab Initio Method ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Full Relaxation ◽  
Energy Plane ◽  
Large Charge

The structural and electronic properties of TiC(111) surfaces are calculated using the first-principles total-energy plane-wave pseudopotential method based on density functional theory. As a polar surface, (111) surface shows large charge depletion in the upper part of the atoms, while charge accumulation happens in the inferior part of the atoms, interlayer Ti-C chemical bonds are reinforced and the outermost interlayer distances are largely reduced. Meanwhile, the charge accumulation and depletion for Ti-terminated surface is more than that for C-terminated surface on the same position of the two slabs after full relaxation. The surface energy of C-terminated surface is in the range from 7.61 to 9.83 J/m2, much larger than that of Ti-terminated surface from 3.13 to 1.35 J/m2, and the Ti-terminated surface is thermodynamically more favorable over all of the range of (chemical potential of TiC slab). This present work makes a beneficial attempt at exploring TiC surface as an ab initio method for studying possible nucleation mechanism of Aluminum on it.

Sign in / Sign up

Export Citation Format

Share Document