ELECTRONIC STRUCTURES OF HEAVY-METAL CLUSTERS

1996 ◽  
Vol 03 (01) ◽  
pp. 335-340
Author(s):  
Y. ISHII ◽  
N. WATARI ◽  
S. OHNISHI
Keyword(s):  
Shell Model ◽  
Electronic Structures ◽  
Density Functional ◽  
Local Density ◽  
Model Description ◽  
First Principle ◽  
Electronic Shell ◽  
Hexagonal Close Packed ◽  
The Stability ◽  
Doubly Charged

The electronic structures of small Hg and Pb clusters are studied by the first-principle calculations within the local density-functional approximation. It is found that the stable structure of Hg19 cluster is not polyicosahedral but hexagonal close-packed although the bonding nature is still atom-like with no significant sp-hybridization. The stability of a doubly charged Pb cluster is discussed in connection with the electronic shell-model description. We conclude that the stability of Pb clusters is determined by complicated correlation between the atomic and electronic structures, and the electronic shell model cannot be applied straightforwardly.

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.

scholarly journals Атомная структура и энергия когезии изолированных кластеров SiC

2020 ◽  
Vol 62 (6) ◽  
pp. 974
Author(s):  
Л.И. Овсянникова
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Energy Gap ◽  
Cohesion Energy ◽  
First Principle ◽  
Sphalerite Structure ◽  
Functional Theory ◽  
The Stability ◽  
First Time ◽  
Gap Width

The first-principle calculations of the atomic and electronic structures and cohesion energy of fullerene-like Si60C60 clusters have been carried out. A model of two-layer fullerene-like Si12C12@Si48C48 cluster with mixed sp2/sp3 bonds has been built for the first time. Ab initio calculations are performed in terms of the electron density functional and the hybrid B3LYP functional theory. The stability and the energy gap width of the clusters are estimated in the dependence on its geometry. It is shown that cohesion energy of two-layer fullerene-like Si12C12@Si48C48 cluster exceeds the cohesion energy of the other fullerene-like clusters with the same number of atoms, but is inferior to the SiC cluster with sphalerite structure. The relaxation of two-layer cluster is shift on outward the surface layer occurs.

scholarly journals Атомная структура и энергия когезии кластеров ZnSe и CdSe

2019 ◽  
Vol 61 (4) ◽  
pp. 786
Author(s):  
Л.И. Овсянникова
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Energy Gap ◽  
First Principle ◽  
External Layer ◽  
Functional Theory ◽  
First Principle Calculations ◽  
The Stability ◽  
First Time ◽  
Gap Width

AbstractThe first-principle calculations of the atomic and electronic structures of fullerene-like Zn_ n Se_ n and Cd_ n Se_ n have been carried out for n = 12, 36, 48, and 60. A model of two-layer fullerene-like (ZnSe)_60 and (CdSe)_60 clusters with mixed sp ^2/ sp ^3 bonds has been built for the first time. Ab initio calculations are performed in terms of the electron density functional and the hybrid B3LYP functional theory. The stability and the energy gap width of the clusters are estimated in the dependence on the number of atoms in a cluster and its geometry. It is shown that the relaxation of 1.7–1.8-nm two-layer (ZnSe)_60 and (CdSe)_60 clusters with mixed sp ^2/ sp ^3 bonds is accompanied by splitting out of the external layer.

Crystallographic input data for (001)-, (110)- and (111)-oriented superlattices

2012 ◽  
Vol 68 (4) ◽  
pp. 378-388 ◽  
Author(s):  
Z Touaa ◽  
Nadir Sekkal
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Input Data ◽  
Local Density ◽  
Full Potential ◽  
First Principle ◽  
Functional Approximation ◽  
Local Density Functional ◽  
General Aspects ◽  
Linear Muffin Tin Orbital

General aspects concerned with (001)-, (110)- and (111)-oriented superlattices (SLs) have been investigated. In particular, the symmetry of these systems have been derived and given in detail. As a test, the obtained data have been utilized to calculate electronic structures and gaps of a standard GaAs/AlAs system using an accurate version of the first principle full potential linear muffin-tin orbital (FPLMTO) method based on a local-density functional approximation (LDA).

The tuning effect of the electric field on the physical properties of some typical wurtzite semiconductors

2017 ◽  
Vol 31 (33) ◽  
pp. 1750310 ◽  
Author(s):  
Jia-Ning Li ◽  
San-Lue Hu ◽  
Hao-Yu Dong ◽  
Xiao-Ying Xu ◽  
Jia-Fu Wang ◽  
...  
Keyword(s):  
Electric Field ◽  
Physical Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Great Influence ◽  
Semiconductor Materials ◽  
Functional Theory ◽  
The Stability ◽  
Wurtzite Semiconductors

Under the tuning of an external electric field, the variation of the geometric structures and the band gaps of the wurtzite semiconductors ZnS, ZnO, BeO, AlN, SiC and GaN have been investigated by the first-principles method based on density functional theory. The stability, density of states, band structures and the charge distribution have been analyzed under the electric field along (001) and (00[Formula: see text]) directions. Furthermore, the corresponding results have been compared without the electric field. According to our calculation, we find that the magnitude and the direction of the electric field have a great influence on the electronic structures of the wurtzite materials we mentioned above, which induce a phase transition from semiconductor to metal under a certain electric field. Therefore, we can regulate their physical properties of this type of semiconductor materials by tuning the magnitude and the direction of the electric field.

scholarly journals Electronic Structure and Optical Properties of Co and Fe Doped ZnO

2016 ◽  
Vol 43 ◽  
pp. 23-28 ◽  
Author(s):  
Chun Ping Li ◽  
Ge Gao ◽  
Xin Chen
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Band Gaps ◽  
First Principle ◽  
Functional Theory ◽  
Doped Zno ◽  
Pseudo Potential ◽  
Co Doped

First-principle ultrasoft pseudo potential approach of the plane wave based on density functional theory (DFT) has been used for studying the electronic characterization and optical properties of ZnO and Fe, Co doped ZnO. The results show that the doping impurities change the lattice parameters a little, but bring more changes in the electronic structures. The band gaps are broadened by doping, and the Fermi level accesses to the conduction band which will lead the system to show the character of metallic properties. The dielectric function and absorption peaks are identified and the changes compared to pure ZnO are analyzed in detail.

scholarly journals Tuning Electronic Structures of BN and C Double-Wall Hetero-Nanotubes

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Xueran Liu ◽  
Meijun Han ◽  
Xinjiang Zhang ◽  
Haijun Hou ◽  
Shaoping Pang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Electric Field ◽  
Electronic Structures ◽  
Density Functional ◽  
Transverse Electric ◽  
First Principle ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Double Wall

First principle calculations based on density functional theory with the generalized gradient approximation were carried out to investigate the energetic and electronic properties of carbon and boron nitride double-wall hetero-nanotubes (C/BN-DWHNTs) with different chirality and size, including an armchair (n,n) carbon nanotube (CNT) enclosed in (m,m) boron nitride nanotube (BNNT) and a zigzag (n, 0) CNT enclosed in (m, 0) BNNT. The electronic structure of these DWHNTs under a transverse electric field was also investigated. The ability to tune the band gap with changing the intertube distance (di) and imposing an external electric field (F) of zigzag DWHNTs provides the possibility for future electronic and electrooptic nanodevice applications.

Theory for New Carbon-Based Materials

1992 ◽  
Vol 270 ◽  
Author(s):  
D.W. Brenner ◽  
R.C. Mowrey ◽  
J. W. Mintmire ◽  
J.A. Harrison ◽  
D.H. Robertson ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structures ◽  
Strain Energy ◽  
Density Functional ◽  
Local Density ◽  
Photoelectron Spectra ◽  
Cluster Calculations ◽  
Local Density Functional ◽  
Dynamics Simulations ◽  
Cohesive Energies

ABSTRACTWe review results of our local-density-functional-based cluster calculations and molecular dynamics simulations of fullerenes and related structures. These include predictions of cohesive energies, electronic structures, and photoelectron spectra for a number of pure and chemically substituted fullerenes, studies of the resilience of C60 under severe compression and during surface collisions, simulations of the trapping of Hein the interior of C60, predictions of the strain energy, electronic and elastic properties of graphitic tubules, and simulations of the folding and curling of graphitic ribbons.

First-Principles Study of Helical Silver Single-Wall Nanotubes and Nanowires

2005 ◽  
Vol 900 ◽  
Author(s):  
Shelly L. Elizondo ◽  
John W. Mintmire
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Catalytic Properties ◽  
Local Density ◽  
High Symmetry ◽  
Graphite Sheet ◽  
Preliminary Study ◽  
Single Wall Nanotubes ◽  
Special Case

ABSTRACTWe investigate the electronic structures of extended helical silver single-wall nanotubes (AgSWNTs). Because these helical nanotubes are essentially comprised of n-atom strands winding about the nanotube's axis, we systematically examine, strand by strand, the electronic properties and the number of conduction channels associated with these structures. Herein, we study a special case of high-symmetry nanotubes. Nanotubes with sufficiently large radii were also calculated with a silver atomic chain inserted along the nanotube's axis. The analysis is carried out within a first-principles, all-electron self-consistent local density functional approach (LDF) adapted for helical symmetry. Modeling helical silver (or gold) single-wall nanotubes entails rolling up a sheet of atoms and mapping the atoms onto the surface of a cylinder, comparable to rolling up a graphite sheet for a carbon nanotube. It is well known that controlling the size and shape of silver and gold nanostructures results in the ability to tailor the optical and catalytic properties of these materials. In this preliminary study, we consider changes in the electronic structures of these materials as each nanotube is built strand by strand.

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