Chemical Bonding and Pseudogap in Zn- and Cd-based Compounds with Complex Hexagonal Structures

2003 ◽  
Vol 805 ◽  
Author(s):  
Y. Ishii ◽  
K. Nozawa ◽  
T. Fujiwara
Keyword(s):  
Fermi Level ◽  
Density Of States ◽  
Chemical Bonding ◽  
First Principles ◽  
Electronic Structures ◽  
Unit Cell ◽  
First Principles Calculations ◽  
Electronic Density ◽  
Electronic Density Of States ◽  
Crystal Orbital

ABSTRACTElectronic structures of hexagonal Zn-Mg-Y and Cd58Y13 compounds are studied by first-principles calculations. Both of the systems show deep pseudogap in the electronic density of states near the Fermi level and considered to be stabilized electronically. To illustrate bonding nature of electronic wavefunctions, the crystal orbital Hamilton population (COHP) is calculated for neighboring pairs of atoms in the unit cell. It is found that the bonding nature is changed from bonding to anti-bonding almost exactly at the Fermi level for Zn-Zn and Cd-Cd bonds. On the contrary, for Zn/Cd-Y bonds, both of the states below and above the pseudogap behave as bonding ones. Possible effects of the p-d hybridization are discussed.

The Study of Electronic Density of States and Optical Properties of ZnO Nanotube by First-Principles

2015 ◽  
Vol 713-715 ◽  
pp. 2966-2969
Author(s):  
Yue Fan ◽  
Shao Chang Chen
Keyword(s):  
Optical Properties ◽  
Fermi Level ◽  
Density Of States ◽  
First Principles ◽  
Electronic Density ◽  
Electronic Density Of States ◽  
Zno Nanotube ◽  
Narrow Energy Range ◽  
Wide Energy ◽  
Better Than

In this paper, we studied the electronic density of states (DOS) and optical properties ZnO using first-principles method. We find that the electronic density of states was different in bulk ZnO and ZnO nanotube. The DOS of bulk ZnO spread at wide energy while the DOS of ZnO nanotube concentrated in a narrow energy range. The peak around-18 eV moved to a higher energy. The peaks more than Fermi level concentrated to the Fermi level, which meant the conductivity of ZnO nanotube was better than that of bulk ZnO. We also calculated the optical properties of ZnO nanotube. The optical properties showed that there were peaks around 8 eV, which may come from electrons transition between Zn 3dand O 2pstates. Our calculation provided a reference for the application of ZnO nanotube in optical devices.

Effects of n-Type Dopants on Electronic Properties in 4H-SiC

2015 ◽  
Vol 645-646 ◽  
pp. 325-329
Author(s):  
Jin Long Tang ◽  
Jun Nan Zhong ◽  
Cai Wen
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Of States ◽  
First Principles ◽  
Electronic Structures ◽  
Doping Concentration ◽  
Impurity Level ◽  
First Principles Calculations

Based on first-principles calculations, we have investigated atomic and electronic structures of 4H-SiC crystal doped by N, P and As elements as n-type dopants. We have obtained the bond lengths of the optimization system, as well as the impurity levels, the band structure and the density of states. The results show that the higher impurity level above the Fermi level is observed when 4H-SiC doped by N with concentration as 6.25% in these dopants, and the band gap of 4H-SiC decreases while the doping concentration or the atomic number of dopant increases.

First-principles calculations of electronic structures and ferromagnetism of Fe3Si(001)//MgO(001) films

2018 ◽  
Vol 32 (24) ◽  
pp. 1850272
Author(s):  
Jing Xie ◽  
Quan Xie
Keyword(s):  
Fermi Level ◽  
Density Of States ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Energy Gap ◽  
Covalent Bond ◽  
Total Density ◽  
First Principles Calculations ◽  
Si Films

The first-principles calculations based on density functional theory (DFT) were carried out in investigating electronic structures and ferromagnetism of Fe3Si films epitaxial on MgO(001). Firstly, the various geometric structures of Fe3Si(001)//MgO(001) constructed near lattice constant c = 3.995 Å were optimized to gain the most steady equilibrium state at c = 3.980 Å. Then, the calculated cohesive energy and negative heat of formation indicate that Fe3Si(001)//MgO(001) formed in this manner obtain high structural stability. The calculated results of spin-polarized energy band structures and density of states show that Fe3Si(001)//MgO(001) exhibit the metallic feature whose bonding orbitals are constituted by covalent bond and metallic bond. Two peaks located in both the sides of the Fermi level and the total density of states (TDOS) in this energy range are all due to the Fe 3d states, which implies that the pseudo energy gap exists in the Fermi level and covalent electron orbit hybridization takes place. Ferromagnetism of Fe3Si(001)//MgO(001) are determined by the 3d states of Fe atoms. There are two occupied sites for Fe atoms with different local magnetic moments, which is 1.34 [Formula: see text]/atom for Fe[A, C] atoms and a value of 2.68 [Formula: see text]/atom for Fe[B] atoms, likewise indicating Fe3Si films epitaxial on MgO(001) are ferromagnetic.

EFFECT OF THE LOCAL SUBSTITUTION OF Co FOR Cu(1) ON THE ELECTRONIC STRUCTURE OF YBa2Cu3O7

1993 ◽  
Vol 07 (07) ◽  
pp. 471-481 ◽  
Author(s):  
JIU-YUAN GE ◽  
YUN-SONG ZHOU ◽  
LI-YUAN ZHONG ◽  
HUAI-YU WANG
Keyword(s):  
Electronic Structure ◽  
Fermi Level ◽  
Density Of States ◽  
Recursion Method ◽  
Electronic Density ◽  
One Dimensional ◽  
Electronic Density Of States ◽  
Co Doping

The electronic density of states (DOS) of both pure and Co-substituted YBa 2 Cu 3 O 7 has been calculated by a recursion method. The results show that the total DOS at the Fermi level of YBa 2 Cu 3 O 7 mainly comes from the contributions of the O 2p and Cu 3d orbitals. After Co doping, the O 2p–Cu 3d bonds are destroyed while the O 2p–Co 3d bonds are formed at lower energies, and the total DOS at the Fermi level decreases strikingly. In addition, our results reveal that the CuO chain has a one-dimensional feature.

First-Principles Study on the Clean and Nb Doped TiO2(110)γ-TiAl(111) Interfaces

2012 ◽  
Vol 602-604 ◽  
pp. 555-558 ◽  
Author(s):  
Hui Nan Hao ◽  
Xu Wang ◽  
Fu He Wang
Keyword(s):  
Structural Stability ◽  
Density Of States ◽  
Chemical Bonding ◽  
First Principles ◽  
Adhesion Energy ◽  
First Principles Calculations ◽  
First Principles Study

In this paper, the structural stability, adhesion and chemical bonding of the TiO2 (110)/TiAl (111) interface are investigated by the first-principles calculations. We predict the maximum adhesion energy of 1.91J/m2 of the TiO2/TiAl interface. We also calculated the Nb doped interface, and found that the doped Nb atom prefers to replace the Ti atom at the second layer of TiAl slab. The atomic geometry and density of states are analyzed. The results show that the effect of doped Nb is localized and insignificant on the TiO2 (110)/TiAl(111) interface.

scholarly journals First-principles calculation of electronic density of states and Seebeck coefficient in transition-metal-doped Si–Ge alloys

2021 ◽  
Vol 323 ◽  
pp. 114115
Author(s):  
Ryo Yamada ◽  
Akira Masago ◽  
Tetsuya Fukushima ◽  
Hikari Shinya ◽  
Tien Quang Nguyen ◽  
...  
Keyword(s):  
Transition Metal ◽  
Seebeck Coefficient ◽  
Density Of States ◽  
First Principles ◽  
First Principles Calculation ◽  
Electronic Density ◽  
Electronic Density Of States ◽  
Metal Doped
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