First-Principles Calculation of Conductivity of Ce-C Codoped SnO2 Contacts

The contact is the core element of the vacuum interrupter of the mechanical DC circuit breaker. The electrical conductivity and welding resistance of the material directly affect its stability and reliability. AgSnO2 contact material has low resistivity, welding resistance, and so on. This material occupies an important position of the circuit breaker contact material. This research is based on the first-principles analysis method of density functional theory. The article calculated the lattice constant, enthalpy change, energy band, electronic density of state, charge density distribution, population, and conductivity of Ce, C single-doped, and Ce-C codoped SnO2 systems. The results show that Ce, C single doping, and Ce-C codoping all increase the cell volume and lattice constant. When the elements are codoped, the enthalpy change is the largest, and the thermal stability is the best. It has the smallest bandgap, the most impurity energy levels, and the least energy required for electronic transitions. The 4f orbital electrons of the Ce atom and the 2p orbital electrons of C are the sources of impurity energy near the Fermi level. When the elements are codoped, more impurity energy levels are generated at the bottom of the conduction band and the top of the valence band. Its bandgap is reduced so conductivity is improved. From the charge density and population analysis, the number of free electrons of Ce atoms and C atoms is redistributed after codoping. It forms a Ce-C covalent bond to further increase the degree of commonality of electrons and enhance the metallicity. The conductivity analysis shows that both single-doped and codoped conductivity have been improved. When the elements are codoped, the conductivity is the largest, and the conductivity is the best.

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Theoretical Investigation on Microstructure of the Novel 24R-Type LPSO Phase in Mg97Zn1Y2 Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.233-235.2359 ◽

2011 ◽

Vol 233-235 ◽

pp. 2359-2366

Author(s):

Ping Ying Tang ◽

Meng Xue Zeng ◽

Dong Lin Li ◽

Bi Yu Tang ◽

Li Ming Peng ◽

...

Keyword(s):

First Principles ◽

Density Functional ◽

Stacking Fault ◽

First Principles Calculation ◽

The Novel ◽

Ordered Structure ◽

Density Of State ◽

Electronic Density ◽

Functional Theory ◽

Long Period

The first-principles calculation based on density functional theory has been carried out to study the microstructural feature of the novel 24R-type long period stacking ordered structure in Mg97Zn1Y2alloy. The lattice positions of the Y and Zn atoms are determined theoretically, it is shown that the additive atoms are firstly enriched in the stacking fault layers at the two ends, a small amount are distributed in the interior stacking fault layers of the structure. And the arrangement of these Y and Zn atoms trends to be along the diagonal line of the unit cell. The structural stability is analyzed and the electronic density of state is discussed as well as.

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First-Principles Calculations on Atomic and Electronic Properties of Ge/4H-SiC Heterojunction

Advances in Condensed Matter Physics ◽

10.1155/2018/8010351 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9

Author(s):

Bei Xu ◽

Changjun Zhu ◽

Xiaomin He ◽

Yuan Zang ◽

Shenghuang Lin ◽

...

Keyword(s):

Charge Density ◽

Electronic Properties ◽

Density Of States ◽

First Principles ◽

Density Functional ◽

First Principles Calculation ◽

Partial Density ◽

Total Charge ◽

Relaxation Energy ◽

Total Charge Density

First-principles calculation is employed to investigate atomic and electronic properties of Ge/SiC heterojunction with different Ge orientations. Based on the density functional theory, the work of adhesion, relaxation energy, density of states, and total charge density are calculated. It is shown that Ge(110)/4H-SiC(0001) heterointerface possesses higher adhesion energy than that of Ge(111)/4H-SiC(0001) interface, and hence Ge/4H-SiC(0001) heterojunction with Ge[110] crystalline orientation exhibits more stable characteristics. The relaxation energy of Ge(110)/4H-SiC(0001) heterojunction interface is lower than that of Ge(111)/4H-SiC(0001) interface, indicating that Ge(110)/4H-SiC(0001) interface is easier to form at relative low temperature. The interfacial bonding is analysed using partial density of states and total charge density distribution, and the results show that the bonding is contributed by the Ge-Si bonding.

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First-Principles Calculation of Laser Crystal Multiplet Levels via Hybridized Density Functional Theory and Configuration Interaction within the OLCAO Method

Advance Sustainable Science, Engineering and Technology ◽

10.26877/asset.v1i1.4875 ◽

2019 ◽

Vol 1 (1) ◽

Author(s):

Benjamin Walker

Keyword(s):

Density Functional Theory ◽

Configuration Interaction ◽

First Principles ◽

Density Functional ◽

Energy Levels ◽

Computational Method ◽

First Principles Calculation ◽

Functional Theory ◽

Racah Parameters ◽

Analytic Computation

Computation of highly-localized multiplet energy levels of transition metal dopants is essential to the design of materials such as laser host crystals. A purely first-principles density functional theory-configuration interaction (DFT-CI) hybrid computational method has been developed to accurately compute multiplet energy levels for single atoms of carbon, nitrogen, oxygen, sodium, aluminum, silicon, titanium, and chromium. The multiplet energy levels have been computed with close experimental agreement in terms of magnitude and degeneracy, and the method does not depend on empirical information (i.e. Racah parameters). The computed multiplet energy level results are distributed according to term symbols, which are then compared to experimentally-observed multiplet energy levels. The hybrid method consists of analytic computation of two-electron integrals via the DFT-based orthogonalized linear combination of atomic orbitals (OLCAO) method, which are subsequently used as input for the CI-based discrete variational multi-electron (DVME) method to obtain the multiplet energy values.Keywords: exchange-correlation; elecron repulsion integral; multiplet; DVME; OLCAO; density functional theory; configuration interaction

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The structural, electronic and optical properties of Au–ZnO interface structure from the first-principles calculation

Modern Physics Letters B ◽

10.1142/s0217984918501075 ◽

2018 ◽

Vol 32 (07) ◽

pp. 1850107 ◽

Cited By ~ 2

Author(s):

Jin-Rong Huo ◽

Lu Li ◽

Hai-Xia Cheng ◽

Xiao-Xu Wang ◽

Guo-Hua Zhang ◽

...

Keyword(s):

Optical Properties ◽

Density Of States ◽

First Principles ◽

Density Functional ◽

Interface Structure ◽

First Principles Calculation ◽

Total Density ◽

Electronic Density ◽

Electronic And Optical Properties ◽

Interface Structures

The interface structure, electronic and optical properties of Au–ZnO are studied using the first-principles calculation based on density functional theory (DFT). Given the interfacial distance, bonding configurations and terminated surface, we built the optimal interface structure and calculated the electronic and optical properties of the interface. The total density of states, partial electronic density of states, electric charge density and atomic populations (Mulliken) are also displayed. The results show that the electrons converge at O atoms at the interface, leading to a stronger binding of interfaces and thereby affecting the optical properties of interface structures. In addition, we present the binding energies of different interface structures. When the interface structure of Au–ZnO gets changed, furthermore, varying optical properties are exhibited.

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First-Principles Calculation of the Electronic Structure of SrTiO3

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.750-752.1199 ◽

2013 ◽

Vol 750-752 ◽

pp. 1199-1202

Author(s):

Jiang Ni Yun ◽

Tieen Yin ◽

Zhi Yong Zhang

Keyword(s):

Electronic Structure ◽

Brillouin Zone ◽

First Principles ◽

Density Functional ◽

Population Analysis ◽

Density Difference ◽

First Principles Calculation ◽

Cubic Phase ◽

High Symmetry ◽

Electronic Density

The electronic structure, band structure, density of states (DOS) and electronic density difference of paraelectric SrTiO3 in the cubic phase were performed by the first-principles calculation based on the density functional theory (DFT). The energy levels of high symmetry points in the Brillouin zone were listed and Mulliken population analysis was performed for valence bond structures. The top valence band of SrTiO3 is at the R point, and the minimum of the conduction bands is at the Γ point. The calculated value for indirect band gap is 1.84eV in the Brillouin zone. As in other perovskite ABO3 ferroelectrics, the population analysis, DOS and electron density difference show that there is a very strong hybridization between the Ti3d and O2p states in the valence bands, which is responsible for the ferroelectricity tendency.

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Pros and cons of time-dependent hybrid density functional approach to optical spectra of solids: a case study of CeO2

Physical Chemistry Chemical Physics ◽

10.1039/d1cp02049h ◽

2021 ◽

Author(s):

Huai-Yang Sun ◽

Shuo-Xue Li ◽

Hong Jiang

Keyword(s):

First Principles ◽

Density Functional ◽

Computational Cost ◽

Optical Spectra ◽

First Principles Calculation ◽

Many Body ◽

Many Body Perturbation Theory ◽

Pros And Cons ◽

Hybrid Density Functional

Prediction of optical spectra of complex solids remains a great challenge for first-principles calculation due to the huge computational cost of the state-of-the-art many-body perturbation theory based GW-Bethe Salpeter equation...

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Strain Conditions for the Inverse Heusler Type Fully Compensated Spin-Gapless Semiconductor Ti2MnAl: A First-Principles Study

Materials ◽

10.3390/ma11112091 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2091 ◽

Cited By ~ 13

Author(s):

Tie Yang ◽

Liyu Hao ◽

Rabah Khenata ◽

Xiaotian Wang

Keyword(s):

Thermodynamic Properties ◽

First Principles ◽

Density Functional ◽

Theoretical Study ◽

Debye Model ◽

Pressure Effects ◽

First Principles Calculation ◽

Strain Condition ◽

Functional Theory ◽

Future Work

In this work, we systematically studied the structural, electronic, magnetic, mechanical and thermodynamic properties of the fully compensated spin-gapless inverse Heusler Ti2MnAl compound under pressure strain condition by applying the first-principles calculation based on density functional theory and the quasi-harmonic Debye model. The obtained structural, electronic and magnetic behaviors without pressure are well consistent with previous studies. It is found that the spin-gapless characteristic is destroyed at 20 GPa and then restored with further increase in pressure. While, the fully compensated ferromagnetism shows a better resistance against the pressure up to 30 GPa and then becomes to non-magnetism at higher pressure. Tetragonal distortion has also been investigated and it is found the spin-gapless property is only destroyed when c/a is less than 1 at 95% volume. Three independent elastic constants and various moduli have been calculated and they all show increasing tendency with pressure increase. Additionally, the pressure effects on the thermodynamic properties under different temperature have been studied, including the normalized volume, thermal expansion coefficient, heat capacity at constant volume, Grüneisen constant and Debye temperature. Overall, this theoretical study presents a detailed analysis of the physical properties’ variation under strain condition from different aspects on Ti2MnAl and, thus, can provide a helpful reference for the future work and even inspire some new studies and lead to some insight on the application of this material.

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Effect of Alloying Elements V, Cr and Ni on the Electronic Structure and Mechanical Properties of FeAl from First-Principles Calculation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.887-888.378 ◽

2014 ◽

Vol 887-888 ◽

pp. 378-383 ◽

Cited By ~ 2

Author(s):

Yu Chen ◽

Zheng Jun Yao ◽

Ping Ze Zhang ◽

Dong Bo Wei ◽

Xi Xi Luo ◽

...

Keyword(s):

Mechanical Properties ◽

Electronic Structure ◽

Elastic Constants ◽

First Principles ◽

Density Functional ◽

Valence Bond ◽

Ternary Alloys ◽

First Principles Calculation ◽

Structure Stability ◽

Alloying Element

The structure stability, mechanical properties and electronic structures of B2 phase FeAl intermetallic compounds and FeAl ternary alloys containing V, Cr or Ni were investigated using first-principles density functional theory calculations. Several models are established. The total energies, cohesive energies, lattice constants, elastic constants, density of states, and the charge densities of Fe8Al8 and Fe8XAl7 ( X=V, Cr, Ni ) are calculated. The stable crystal structures of alloy systems are determined due to the cohesive energy results. The calculated lattice contants of Fe-Al-X ( X= V, Cr, Ni) were found to be related to the atomic radii of the alloy elements. The calculation and analysis of the elastic constants showed that ductility of FeAl alloys was improved by the addition of V, Cr or Ni, the improvement was the highest when Cr was used. The order of the ductility was as follows: Fe8CrAl7 > Fe8NiAl7 > Fe8VAl7 > Fe8Al8. The results of electronic structure analysis showed that FeAl were brittle, mainly due to the orbital hybridization of the s, p and d state electron of Fe and the s and p state electrons of Al, showing typical characteristics of a valence bond. Micro-mechanism for improving ductility of FeAl is that d orbital electron of alloying element is maily involved in hybridization of FeAl, alloying element V, Cr and Ni decrease the directional property in bonding of FeAl.

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Structural and Electronic Properties of Orthorhombic Phase Bi2Se3 Based On First-Principles Study

Scientific Research Journal ◽

10.24191/srj.v16i2.6359 ◽

2019 ◽

Vol 16 (2) ◽

pp. 77 ◽

Cited By ~ 1

Author(s):

Muhammad Zamir Mohyedin ◽

Afiq Radzwan ◽

Mohammad Fariz Mohamad Taib ◽

Rosnah Zakaria ◽

Nor Kartini Jaafar ◽

...

Keyword(s):

Electronic Properties ◽

First Principles ◽

Density Functional ◽

Local Density ◽

Computer Code ◽

First Principles Calculation ◽

Generalized Gradient ◽

Exchange Correlation ◽

Percentage Difference ◽

Structural And Electronic Properties

Bi2Se3 is one of the promising materials in thermoelectric devices and very useful out of environmental concern due to its efficiency to perform at room temperature. Based on the first-principles calculation of density functional theory (DFT) by using CASTEP computer code, structural and electronic properties of Bi2Se3 were investigated. The calculation is conducted within the exchange-correlation of local density approximation (LDA) and generalized gradient approximation within the revision of Perdew-Burke-Ernzerhof (GGA-PBE) functional. It was found that the results are consistent with previous works of theoretical study with small percentage difference. LDA exchange-correlation functional method is more accurate and have a better agreement than GGA-PBE to describe the structural properties of Bi2Se3 which consist of lattice parameters. LDA functional also shown more accurate electronic structure of Bi2Se3 that consist of band structure and density of states (DOS) which consistent with most previous theoretical works with small percentage difference. This study proves the reliability of CASTEP computer code and show LDA exchange-correlation functional is more accurate in describing the nature of Bi2Se3 compared to the other functionals.

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