scholarly journals Robust Spin-Gapless Behavior in the Newly Discovered Half Heusler Compound MnPK

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3117 ◽  
Author(s):  
Jiaxue You ◽  
Jieting Cao ◽  
Rabah Khenata ◽  
Xiaotian Wang ◽  
Xunan Shen ◽  
...  
Keyword(s):  
First Principles ◽  
Experimental Studies ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Good Resistance ◽  
Heusler Compound ◽  
New Class ◽  
Hubbard U ◽  
Calculation Results ◽  
Spin Gapless Semiconductors

Spin gapless semiconductors have aroused high research interest since their discovery and a lot of effort has been exerted on their exploration, in terms of both theoretical calculation and experimental verification. Among different spin gapless materials, Heusler compounds stand out thanks to their high Curie temperature and highly diverse compositions. Especially, both theoretical and experimental studies have reported the presence of spin gapless properties in this kind of material. Recently, a new class of d0 − d Dirac half Heusler compound was introduced by Davatolhagh et al. and Dirac, and spin gapless semiconductivity has been successfully predicted in MnPK. To further expand the research in this direction, we conducted a systematical investigation on the spin gapless behavior of MnPK with both generalized gradient approximation (GGA) and GGA + Hubbard U methods under both uniform and tetragonal strain conditions by first principles calculation. Results show the spin gapless behavior in this material as revealed previously. Different Hubbard U values have been considered and they mainly affect the band structure in the spin-down channel while the spin gapless feature in the spin-up direction is maintained. The obtained lattice constant is very well consistent with a previous study. More importantly, it is found that the spin gapless property of MnPK shows good resistance for both uniform and tetragonal strains, and this robustness is very rare in the reported studies and can be extremely interesting and practical for the final end application. This study elaborates the electronic and magnetic properties of the half Heusler compound MnPK under uniform and tetragonal strain conditions, and the obtained results can give a very valuable reference for related research works, or even further motivate the experimental synthesis of the relative material.

First-Principles Studies of Structural, Electronic and Magnetic Properties of the CrS, CrSe and CrTe Compounds

SPIN ◽  
2018 ◽  
Vol 08 (04) ◽  
pp. 1850019 ◽  
Author(s):  
A. Belkadi ◽  
K. O. Obodo ◽  
Y. Zaoui ◽  
H. Moulkhalwa ◽  
L. Beldi ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Experimental Studies ◽  
First Principles Calculation ◽  
Energy Structure ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Electronic And Magnetic Properties ◽  
Metallic Ferromagnetism ◽  
Half Metallic Ferromagnetism

Using first-principles calculation within the generalized gradient approximation (GGA) and [Formula: see text] (Hubbard Coulomb onsite correction), we investigated the structural, electronic and magnetic properties of CrS, CrSe and CrTe compounds in different phases. We found that the NaCl phase is the lowest energy structure in comparison to the other investigated phases within the [Formula: see text] approach for CrS, CrSe and CrTe compounds. The CrX compounds investigated in the NaCl phase are all half-metallic ferromagnets with a net magnetic moment of 4.0[Formula: see text][Formula: see text] within the [Formula: see text] approximation. From the density of states profile and charge density distribution, the observed half-metallic ferromagnetism in the CrS, CrSe and CrTe compounds is due to the spin polarized 3[Formula: see text] orbitals of the Cr atoms. The observed stable half-metallic ferromagnetism in the NaCl phase of the CrS, CrSe and CrTe compounds should motivate further experimental studies on the possible application of these compounds as spintronic materials.

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

2019 ◽  
Vol 16 (2) ◽  
pp. 77 ◽  
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.

First-Principles Calculation for Improving Room Temperature Ductility of B2-NiAl by Fe

2011 ◽  
Vol 327 ◽  
pp. 94-99
Author(s):  
Yu Xiang Lu ◽  
Guo Liang Qi ◽  
Liang Cheng
Keyword(s):  
First Principles ◽  
Room Temperature ◽  
Nearest Neighbor ◽  
Function Theory ◽  
Population Analysis ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Room Temperature Ductility ◽  
The Impact

Generalized gradient approximation (GGA) of the density function theory (DFT) was applied to calculate many properties including density of states, population analysis and electron density in NiAl and NiAl(Fe) to investigate the mechanism of improving room temperature ductility of B2-NiAl by Fe. It was shown that the strong bond to Al p and Ni d hybridization, which leads to the embrittlement of B2-NiAl at room temperature. Addition of Fe, which is beneficial to improve ambient ductility of B2-NiAl, weakens the impact of the bond to Al p and Ni d hybridization and enhances the interaction among next-nearest-neighbor Ni atoms to make the charge distribution uniform along <100>.

First Principles Calculation on Adsorption of S on Impurity Fe (100)

2012 ◽  
Vol 472-475 ◽  
pp. 1538-1543
Author(s):  
Qiang Luo ◽  
Zhi Zhang ◽  
Qiang Zhang ◽  
Tai He Shi ◽  
Zeng Ling Ran
Keyword(s):  
Electronic Properties ◽  
Density Function ◽  
Molecular Orbital ◽  
Adsorption Energy ◽  
First Principles ◽  
Function Theory ◽  
Density Function Theory ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation

Using the first principles method, which is based on the density function theory (DFT), the structures and electronic properties of S atoms are adsorbed on the Fe (100) surface for X(X is Cr, Ni, Mo, C, Mn ,Si,P and S) impurities in Fe, and their molecular orbital and absorption energies were calculated with the generalized gradient approximation. The results show that S adsorbed on H site for Cr, Ni, Mn, C and Mo impurities in Fe is stable but for Si, S and P is B site. The adsorption energy for Ni in impurity Fe is almost nearby for the purity Fe and the effect for Ni in S absorption on Fe (100) surface is very small. In order to prevent S absorption on Fe surface，we can reduce the percentage of Ni.

Site Preference of Refractory Elements in Ni-Based Single-Crystal Superalloys Alloying with Ru: From First Principles

2012 ◽  
Vol 554-556 ◽  
pp. 3-12
Author(s):  
Jian Jun Cui ◽  
Fei Sun ◽  
Jian Xin Zhang
Keyword(s):  
Binding Energy ◽  
Single Crystal ◽  
First Principles ◽  
First Principles Calculation ◽  
Partial Density ◽  
Site Preference ◽  
Strengthening Effect ◽  
Mulliken Population ◽  
Calculation Results ◽  
Partitioning Behavior

A first principles calculation method was used to investigate the site preference of Ruthenium (Ru) at the γ/γ′ interface in Ni-based single-crystal superalloys. The calculation results show that the addition of Ru can decrease the total energy and the binding energy of γ/γ′ interface, which may result in an improved microstructure stability of Ni-based single-crystal superalloys. Moreover, by calculation, it is also found that Ru can stabilize both γ and γ′ phases and have a preference for Ni site at the coherent γ/γ′ interface. When Ru substitutes the central Ni at the γ/γ′ interface, a reverse partitioning of W, Re and Cr occurs; while the partitioning behavior of Mo is not affected. The influence of Ru on the partitioning behavior of W, Re and Cr in γ′-Ni3Al was studied by Dmol3 calculation as well. The calculation results show that W, Re and Cr have a preference for Ni site in γ′- Ni3Al with Ru alloying. When Ru substitutes the central Ni atom, the site preference of W, Re and Cr varies accordingly. Furthermore, electronic structure analysis of γ/γ′ interface and γ′-Ni3Al in terms of Mulliken population and partial density of states (PDOS) was performed to understand the alloying mechanism of Ru in Ni-based single-crystal superalloys. The results show that the strengthening effect of Ru alloying is mainly due to the reduction in binding energy of Ru as well as a p-orbital hybridization between Ru and the host atoms.

Investigation of Electronic Structures of F-Doped TiO2 by First-Principles Calculation

2009 ◽  
Vol 620-622 ◽  
pp. 647-650 ◽  
Author(s):  
Ying Cui ◽  
Hao Du ◽  
Li Shi Wen
Keyword(s):  
Photocatalytic Activity ◽  
First Principles ◽  
Electronic Structures ◽  
Lower Energy ◽  
Anatase Tio2 ◽  
First Principles Calculation ◽  
Visible Light Region ◽  
Doped Tio2 ◽  
Light Region ◽  
Calculation Results

F-doped TiO2 has exhibited superior photocatalytic activity. However, its electronic structures and photocatalysis mechanism are still unclear. In the present work, the structural optimization and electronic structure of F-doped anatase TiO2 have been investigated by means of the first-principles pseudopotential total energy method. It has been demonstrated that F doping would modify the valence band at the lower energy direction in the F-doped TiO2. Calculation results confirm that doping of fluorine would not shift the absorption edge into the visible light region. Instead, we attributed its photocatalytic activity to the enhancement of the oxidative power of F-doped TiO2.

scholarly journals Structural and electronic properties of the spinel Li4Ti5O12

2019 ◽  
Vol 20 (46) ◽  
pp. 7-12 ◽  
Author(s):  
Sarantuya Lkhagvajav ◽  
Namsrai Tsogbadrakh ◽  
Enkhjargal Enkhbayar ◽  
Sevjidsuren Galsan ◽  
Pagvajav Altantsog
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Experimental Studies ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural And Electronic Properties ◽  
Hubbard U ◽  
Uv Visible

In this study, the structure and electronic properties of the spinel compound Li4Ti5O12 (LTO) are investigated both theoretical and experimental methods. The experimental studies of structural and electronic properties were performed by X-ray diffraction and UV-visible spectroscopy. The first principles calculations allowed to establish the relationship between the structure and electronic properties. The spinel type structure of LTO is refined by the Rietveld analysis using the X-ray diffraction (XRD). The band gap of LTO was determined to be 3.55 eV using the UV-visible absorption spectra. The Density functional theory (DFT) augmented without and with the Hubbard U correction (GGA and GGA +U+J0) is used to elucidate the electronic structure of LTO. We have performed systematic studies of the first principles calculations based on the GGA and GGA+U for the crystal structure and electronic properties of spinel LTO. We propose that a Hubbard U correction improves the DFT results.

Mo-doping allows high performance for a perovskite cathode applied in proton-conducting solid oxide fuel cells

2021 ◽  
Author(s):  
Xiaomei Li ◽  
Yinhua Liu ◽  
Wenyun Liu ◽  
Chao Wang ◽  
Xi Xu ◽  
...  
Keyword(s):  
Solid Oxide Fuel Cells ◽  
First Principles ◽  
High Performance ◽  
Experimental Studies ◽  
Solid Oxide ◽  
First Principles Calculation ◽  
Oxide Fuel ◽  
Migration Ability ◽  
Mo Doping ◽  
Proton Migration

Experimental studies integrated with first-principles calculation revealed that the Mo-doping strategy allows the traditional Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) perovskite cathode to show improved hydration ability and proton migration ability, leading to a...

scholarly journals First-Principles Calculation of Transition Metal Hyperfine Coupling Constants with the Strongly Constrained and Appropriately Normed (SCAN) Density Functional and its Hybrid Variants

2019 ◽  
Vol 5 (4) ◽  
pp. 69 ◽  
Author(s):  
Dimitrios A. Pantazis
Keyword(s):  
Transition Metal ◽  
First Principles ◽  
Density Functional ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
First Principles Calculation ◽  
Chemical System ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Hyperfine Coupling Constants

Density functional theory (DFT) is used extensively for the first-principles calculation of hyperfine coupling constants in both main-group and transition metal systems. As with many other properties, the performance of DFT for hyperfine coupling constants is of variable quality, particularly for transition metal complexes, because it strongly depends on the nature of the chemical system and the type of approximation to the exchange-correlation functional. Recently, a meta-generalized-gradient approximation (mGGA) functional was proposed that obeys all known exact constraints for such a method, known as the Strongly Constrained and Appropriately Normed (SCAN) functional. In view of its theoretically superior formulation a benchmark set of complexes is used to assess the performance of SCAN for the challenging case of transition metal hyperfine coupling constants. In addition, two global hybrid versions of the functional, SCANh and SCAN0, are described and tested. The values computed with the new functionals are compared with experiment and with those of other DFT approximations. Although the original SCAN and the SCAN-based hybrids may offer improved hyperfine coupling constants for specific systems, no uniform improvement is observed. On the contrary, there are specific cases where the new functionals fail badly due to a flawed description of the underlying electronic structure. Therefore, despite these methodological advances, systematically accurate and system-independent prediction of transition metal hyperfine coupling constants with DFT remains an unmet challenge.

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