scholarly journals Ab initio study of optical and bulk properties of cesium lead halide perovskite solid solutions

2019 ◽  
Vol 33 (31) ◽  
pp. 1950386
Author(s):  
Vladimir Saleev ◽  
Alexandra Shipilova
Keyword(s):  
Solid Solutions ◽  
First Principles ◽  
Disordered Systems ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Bulk Properties ◽  
The Density Functional Theory ◽  
Halide Perovskite ◽  
Lead Halide

The first-principles calculations of band gaps and bulk moduli of cesium lead halide perovskite solid solutions, [Formula: see text] and [Formula: see text], are performed at the level of general gradient approximation of the density functional theory. We use supercell approach for computational modeling of disordered systems, which gives a description of the properties of the structure baasing on the average over a set of multiple configurations, namely distributions of different species over a given set of atomic positions. The calculations were performed with the CRYSTAL14 program package. The dependence of the band gap and bulk modulus on the content [Formula: see text] are investigated over the whole range [Formula: see text].

scholarly journals Electronic, optical and thermoelectric properties of Fe2ZrP compound determined via first-principles calculations

RSC Advances ◽  
2019 ◽  
Vol 9 (44) ◽  
pp. 25900-25911 ◽  
Author(s):  
Esmaeil Pakizeh ◽  
Jaafar Jalilian ◽  
Mahnaz Mohammadi
Keyword(s):  
Density Functional Theory ◽  
Thermoelectric Properties ◽  
First Principles ◽  
Density Functional ◽  
Transport Theory ◽  
First Principles Calculations ◽  
Boltzmann Transport ◽  
Functional Theory ◽  
Boltzmann Transport Theory ◽  
The Density Functional Theory

In this study, based on the density functional theory and semi-classical Boltzmann transport theory, we investigated the structural, thermoelectric, optical and phononic properties of the Fe2ZrP compound.

scholarly journals Effect of Defects on Spontaneous Polarization in Pure and Doped LiNbO3: First-Principles Calculations

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 100 ◽  
Author(s):  
Weiwei Wang ◽  
Dahuai Zheng ◽  
Mengyuan Hu ◽  
Shahzad Saeed ◽  
Hongde Liu ◽  
...  
Keyword(s):  
Spontaneous Polarization ◽  
First Principles ◽  
Density Functional ◽  
Lattice Distortion ◽  
Stable Structure ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Specific Configuration ◽  
The Relationship

Numerous studies have indicated that intrinsic defects in lithium niobate (LN) dominate its physical properties. In an Nb-rich environment, the structure that consists of a niobium anti-site with four lithium vacancies is considered the most stable structure. Based on the density functional theory (DFT), the specific configuration of the four lithium vacancies of LN were explored. The results indicated the most stable structure consisted of two lithium vacancies as the first neighbors and the other two as the second nearest neighbors of Nb anti-site in pure LN, and a similar stable structure was found in the doped LN. We found that the defects dipole moment has no direct contribution to the crystal polarization. Spontaneous polarization is more likely due to the lattice distortion of the crystal. This was verified in the defects structure of Mg2+, Sc3+, and Zr4+ doped LN. The conclusion provides a new understanding about the relationship between defect clusters and crystal polarization.

First Principles Calculations of Electronic Structure and Optical Properties of Cu-Doped SnS2

2013 ◽  
Vol 373-375 ◽  
pp. 1965-1969
Author(s):  
Kun Nan Qin ◽  
Ling Zhi Zhao ◽  
Yong Mei Liu ◽  
Fang Fang Li ◽  
Chao Yang Cui
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Optical Absorption Coefficient ◽  
Impurity Level ◽  
First Principles Calculations ◽  
Absorption Region ◽  
Functional Theory ◽  
The Density Functional Theory

The electronic structure and optical properties of Cu-doped SnS2with Sn-substituted content of 0, 12.5 and 37.5 at.% were successfully calculated by the first principles plane-wave pseudopotentials based on the density functional theory. It is found that the intermediate belts appear near the Fermi level and the energy band gap becomes narrower after the doping of the Cu atoms. The absorption peaks show a remarkable redshift and the absorption region broadens relatively after introducing acceptor impurity level. When Sn atoms of 37.5 at% were substituted by Cu, the optical absorption coefficient is significantly improved in the frequency range below 5.58 eV and over 8.13 eV.

Pressure-Induced Tunable Magnetism and Half-Metallic Stability in Co2FeGa Heusler Alloy

2013 ◽  
Vol 477-478 ◽  
pp. 1303-1306
Author(s):  
Qin Xiang Gao
Keyword(s):  
Fermi Level ◽  
First Principles ◽  
Density Functional ◽  
High Energy ◽  
First Principles Calculations ◽  
Half Metallicity ◽  
Functional Theory ◽  
Half Metallic ◽  
Heusler Compound ◽  
The Density Functional Theory

Using the first-principles calculations within the density functional theory (DFT), we have investigated the structure, magnetism and half-metallic stability of Co2FeGa Heusler compound under pressure from 0 to 50GPa. The results revel that the lattice constant is gradually shrank and total magnetic moment in per unit slightly decreased with increasing pressure, respectively. Moreover, with the increase of the pressure, the Fermi level will move towards high-energy orientation. When the pressure reaches at 30GPa the most stable half-metallicity is observed which the Fermi level is located at the middle of the spin-minority gap.

Ab Initio Study of the Structural and Mechanical Properties of Hf-Si-N

2010 ◽  
Vol 139-141 ◽  
pp. 22-25 ◽  
Author(s):  
Xin Tan ◽  
Yu Qing Li ◽  
Xue Jie Liu ◽  
De Gong Liu
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Cohesive Energy ◽  
Density Functional ◽  
Substitutional Solid Solution ◽  
Lattice Parameter ◽  
Solution Phase ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory

The structural and elastic properties of HfN and Hf-Si-N have been studied, using first principles calculations based on the density functional theory. These calculations provide the lattice parameter, cohesive energy and elastic constants of fcc (NaCl)-HfN, the N-deficient Hf-Si-N and the Hf-deficient Hf-Si-N solution phase. In order to study the relative stability, binding energy of all configurations has been calculated. The results showed that it was difficult to add a Si atom into the center of the HfN cell because the cohesive energy decreased. However, if an Hf atom or an N atom was missing in the HfN, a silicon atom was possible to occupy the vacant site and form the Hf-Si-N substitutional solid solution. Moreover, the bulk modulus, shear modulus and elastic modulus increased accordingly, the mechanical properties were improved.

scholarly journals Phase Stability in U-6Nb Alloy Doped with Ti from the First Principles Theory

2020 ◽  
Vol 10 (10) ◽  
pp. 3417
Author(s):  
Alexander Landa ◽  
Per Söderlind ◽  
Amanda Wu
Keyword(s):  
Phase Stability ◽  
First Principles ◽  
Density Functional ◽  
Room Temperature ◽  
Rapid Quenching ◽  
Quantum Mechanical ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Effect Of Impurities

First-principles calculations within the density-functional-theory (DFT) approach are conducted in order to explore and explain the effect of small amounts of titanium on phase stability in the U-6Nb alloy. During rapid quenching from high to room temperature, metastable phases α′ (orthorhombic), α″ (monoclinic), and γ0 (tetragonal) can form, depending on Nb concentration. Important mechanical properties depend on the crystal structure and, therefore, an understanding of the effect of impurities on phase stability is essential. Insights on this issue are obtained from quantum-mechanical DFT calculations. The DFT framework does not rely on any material-specific assumptions and is therefore ideal for an unbiased investigation of the U-Nb system.

Quantum-chemical study of nitrogen and magnesium co-doping in α-Cr2O3

2016 ◽  
Vol 30 (14) ◽  
pp. 1650219
Author(s):  
Soraya Jácome ◽  
Arvids Stashans
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Text Type ◽  
Co Doping ◽  
The Density Functional Theory

Study of corundum-type chromium oxide ([Formula: see text]-Cr2O3) crystal doped with the nitrogen and magnesium impurities has been carried out through the use of first-principles calculations based on the density functional theory (DFT) and generalized gradient approximation (GGA). Three cases corresponding different impurity–impurity distances have been considered. Structural, electronic and magnetic properties have been studied for all co-doping cases. The [Formula: see text]-type electrical conductivity was found when distance between the Mg and N atoms is equal to 4.10 Å. The results obtained are consistent with the available experimental data.

Theoretical calculations of stability, mechanical and thermodynamic properties of IVA group Willemite-II nitrides

2015 ◽  
Vol 14 (04) ◽  
pp. 1550024 ◽  
Author(s):  
Ying-Chun Ding ◽  
Min Chen ◽  
Wen-Juan Wu
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Mechanical Anisotropy ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Good Agreement

The structural stability and mechanical and thermodynamic properties of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) are calculated by first-principles calculations based on the density functional theory. The calculated lattice parameters and elastic constants of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) are in good agreement with the experimental data and previously calculated values. WII- A 3 N 4 ( A=C , Si , Ge and Sn ) compounds are also found to be thermodynamically and mechanically stable. The results suggest that hardness of WII- C 3 N 4 is the hardest of these C 3 N 4 polymorphs. The hardness of WII- Sn 3 N 4 is the smallest among WII- A 3 N 4 ( A=C , Si , Ge and Sn ). Furthermore, the mechanical anisotropy, Debye temperature, the minimum thermal conductivity and thermodynamic properties of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) compounds can be investigated.

First-principles calculations of the electronic structure of C20, electric field, and monomer interaction effects

2013 ◽  
Vol 91 (1) ◽  
pp. 81-84
Author(s):  
Aqeel Mohsin Ali
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Relative Stabilities ◽  
The Density Functional Theory ◽  
Field Dependent

The density functional theory calculations are applied for C20 cage fullerenes. Furan, pyrole, and phenylvinyle monomers are made to interact with a C20 cage at the same C position. An electric field was applied with varying strength. Computations were carried out for all cases at the B3LYP/6-31G* level. The structure, energetic, and relative stabilities of the compounds were compared with each other and analyzed. In addition, the electric field dependent and independent electronic transition spectra of the proposed stable neutral C20 cage are investigated.

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