Electronic bonding characteristics of hydrogen in bcc iron: Part I. Interstitials

1996 ◽  
Vol 11 (9) ◽  
pp. 2206-2213 ◽  
Author(s):  
Yoshio Itsumi ◽  
D. E. Ellis
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Lattice Relaxation ◽  
Experimental Result ◽  
Functional Formalism ◽  
Discrete Variational Method ◽  
Bcc Iron ◽  
Bond Strengths ◽  
Bonding Characteristics ◽  
Structure Calculations

Electronic structure calculations were carried out for bcc iron (Fe) clusters with or without hydrogen (H), and also involving a vacancy, using the self-consistent Discrete Variational method (DV-Xα) within the local density functional formalism. Bonding characteristics investigated show the following: (i) Interstitial H notably decreases interatomic Fe–Fe bond strengths, but acts over a small distance (within 0.3 nm). (ii) In the perfect Fe lattice field, interstitial H feels a repulsive force at any site. As a result of lattice relaxation, volume expansion may be expected. (iii) H in combination with a vacancy prefers a position shifted from the octahedral site toward the vacancy. This is fairly consistent with an experimental result.

First-Principles Investigation of the Alloying Effect of Mn and Cr in the Kink on the Edge Dislocation in BCC Iron

2008 ◽  
Vol 272 ◽  
pp. 61-70
Author(s):  
Zheng Chen Qiu ◽  
Li Qun Chen
Keyword(s):  
Edge Dislocation ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Interatomic Interaction ◽  
Dislocation Motion ◽  
Binding Energies ◽  
Pinning Effect ◽  
Discrete Variational Method ◽  
Bcc Iron

Using the first-principles self-consistent discrete variational method based on density functional theory, we investigated the energetics and the electronic structure of 3d impurity Mn and Cr in the kink on the [100](010) edge dislocation in bcc iron. The calculations of binding energies show that both Mn and Cr can stabilize the system containing kink. We also calculate the structural energy, the interatomic energy, the local density of states and the charge density difference. The results indicate that both Mn and Cr in the kink can enhance the interatomic interaction between the impurity atom and the neighboring Fe atoms due to the hybridization of impurity d-Fe d orbitals. The introduction of the Mn and Cr impurity leads to a strong pinning effect on the dislocation motion in bcc iron, which may explain the solid solute hardening of Mn and Cr.

Magnetic Properties of Embedded Rh Clusters in Ni Matrix

1995 ◽  
Vol 384 ◽  
Author(s):  
Zhi-Qiang Li ◽  
Yuichi Hashi ◽  
Jing-Zhi Yu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Functional Formalism ◽  
Rhodium Clusters ◽  
Spin Polarized ◽  
Local Density Functional

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.

scholarly journals VIBRATIONAL MODES IN SMALL Agn, Aun CLUSTERS: A FIRST PRINCIPLE CALCULATION

2009 ◽  
Vol 23 (31) ◽  
pp. 5819-5834 ◽  
Author(s):  
OLCAY ÜZENGI AKTÜRK ◽  
OĞUZ GÜLSEREN ◽  
MEHMET TOMAK
Keyword(s):  
Normal Mode ◽  
Density Functional ◽  
Local Density ◽  
Scanning Tunneling ◽  
Generalized Gradient ◽  
Functional Formalism ◽  
First Principle Calculation ◽  
Pseudopotential Calculations ◽  
Normal Mode Calculations ◽  
Small Clusters

Although the stable structures and other physical properties of small Ag n and Au n, were investigated in the literature, phonon calculations are not done yet. In this work, we present plane-wave pseudopotential calculations based on density-functional formalism. The effect of using the generalized gradient approximation (GGA) and local density approximation (LDA) to determine the geometric and electronic structure and normal mode calculations of Ag n and Au n, is studied up to eight atoms. Pure Au n and Ag n clusters favor planar configurations. We calculated binding energy per atom. We have also calculated the normal mode calculations and also scanning tunneling microscope (STM) images for small clusters for the first time.

Electronic Structure of Li-Impurities in ZnSe.

1989 ◽  
Vol 163 ◽  
Author(s):  
T. Oguchi ◽  
T. Sasaki ◽  
H. Katayama-Yoshida
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Local Density ◽  
Lattice Relaxation ◽  
Interstitial Site ◽  
Functional Approach ◽  
Tetrahedral Interstitial Site ◽  
Total Energies ◽  
The Stability ◽  
Impurity Sites

AbstractElectronic properties of ZnSe with a Li impurity are investigated with use of the local-density-functional approach. The electronic structures are calculated for different impurity sites by taking the neighboring lattice relaxation into account. By comparing their total energies, the stability of the Li impurity in ZnSe is discussed. It is proposed that the Li impurity at the substitutional Zn site might be unstable to the tetrahedral interstitial site with an ionization of Li and a vacancy at the Zn site.

ENHANCEMENT OF Fe MAGNETIC MOMENTS IN FERROMAGNETIC Fe16B2, Fe16C2, AND Fe16N2

1993 ◽  
Vol 07 (01n03) ◽  
pp. 729-732 ◽  
Author(s):  
B.I. MIN
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Local Environment ◽  
Electronic Structure Calculations ◽  
Orbital Contribution ◽  
Large Enhancement ◽  
Band Method ◽  
Structure Calculations

In order to investigate electronic and magnetic properties of Fe16X2 (X=B, C, N) ferromagnet, we have performed electronic structure calculations employing the total energy self-consistent local density functional linearized muffin tin orbital (LMTO) band method. Large enhancement of the magnetic moment is observed in FeII and FeIII, which are located farther from X than FeI. This suggests that the local environment plays a very important role in determining Fe magnetic moments in these compounds. Orbital contribution to the magnetic moment in Fe atoms of Fe16N2 is minor, totalof ~0.6 μB in the unit cell. We have obtained the average magnetic moments per Fe atom, 2.30, 2.40, and 2.50 μB, in Fe16B2, Fe16C2, and Fe16N2, respectively.

SURFACE SENSITIVITY OF VERY LOW ENERGY ELECTRONS

1999 ◽  
Vol 06 (05) ◽  
pp. 631-633 ◽  
Author(s):  
I. BARTOŠ ◽  
W. SCHATTKE
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Quantitative Description ◽  
Low Energy ◽  
Imaginary Component ◽  
Functional Formalism ◽  
Self Energy ◽  
Surface Sensitivity ◽  
Escape Depth ◽  
Low Energies

The surface sensitivity of electron diffraction and of electron spectroscopies is determined by the imaginary component of the electron self-energy. In crystals, the energy and direction dependence of the electron attenuation and of the escape depth should be taken into account at very low energies. Strong anisotropy of the electron attenuation has been obtained around 20 eV from peak shapes in VLEED intensity profiles from (111) transition metal surfaces. Extension of the local density approximation in the density functional formalism provides quantitative description of the electron self-energy. The one-step model of angular resolved photoemission incorporating the self-energy predicts a strong energy and angle dependence of the escape depth of low energy photoelectrons emitted from GaAs(110).

Electronic structure and doping effect of Ni and Co in the kink on the edge dislocation of bcc iron

2007 ◽  
Vol 261-262 ◽  
pp. 37-46 ◽  
Author(s):  
Li Qun Chen ◽  
Zheng Chen Qiu
Keyword(s):  
Electronic Structure ◽  
Impurity Atom ◽  
Edge Dislocation ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Discrete Variational Method ◽  
Solid Solution Softening ◽  
Bcc Iron ◽  
3D Impurities

Using the first-principles self-consistent discrete variational method based upon density functional theory, we investigated the energetics and the electronic structure of the 3d impurities Ni and Co in a kink on the [100](010) edge dislocation (ED) in bcc iron. The calculated results show that the interatomic energies between the impurity atom and the neighboring host atoms decrease. The bonding for the impurity atom (Ni, Co) and the neighboring host Fe atoms is weaker than that for an Fe atom at the X site and the corresponding atoms in the clean kink. These results indicate that sideways motion of the kink in the <100>{010} ED is accelerated by an impurity atom such as Ni or Co and that, consequently, the presence of impurities increases the dislocation mobility, thus leading to solid-solution softening.

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