scholarly journals Pressure Tuned Structural, Electronic and Elastic Properties of U3Si2C2: A First Principles Study

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1420
Author(s):  
Moran Bu ◽  
Yaolin Guo ◽  
Diwei Shi ◽  
Zhen Liu ◽  
Jiexi Song ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Density Functional ◽  
Structural Characteristics ◽  
Extreme Environments ◽  
Functional Theory ◽  
Dominant Position ◽  
Lattice Volume ◽  
Calculation Results ◽  
Service Behavior ◽  
Accident Conditions

U3Si2C2 is expected to be a new nuclear fuel as a ternary compound of uranium, silicon and carbon. However, the relevant research on U3Si2C2 under accident conditions is rarely reported. Hence it is necessary to explore the service behavior of the potential U-Si-C ternary nuclear fuel in extreme environments. In this work, the structural characteristics, electronic behaviors and mechanical properties of U3Si2C2, such as stable crystalline structures, density of states, charge distributions, electron localization function, electronic thermal conductivity and elastic modulus under extreme high pressure are calculated by density functional theory. The calculation results show that the lattice volume sharply increases when the external stress reached 9.8 GPa. Ionic and metallic nature coexist as to the bonding characteristics of U3Si2C2, and the ionic takes the dominant position in bonding. The toughness of U3Si2C2 is predicted to be better compared to U3Si2. Our theoretical investigation may help with the application of U3Si2C2-based fuel and the design of ternary uranium fuels.

scholarly journals Comparative Study on Electronic Structure and Optical Properties of α-Fe2O3, Ag/α-Fe2O3 and S/α-Fe2O3

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 424
Author(s):  
Cuihua Zhao ◽  
Baishi Li ◽  
Xi Zhou ◽  
Jianhua Chen ◽  
Hongqun Tang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electronic Structures ◽  
Density Functional ◽  
Peak Strength ◽  
Visible Range ◽  
High Symmetry ◽  
Functional Theory ◽  
Optical Absorption Peak ◽  
Calculation Results

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe2O3 were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe2O3 crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe2O3 with that of pure α-Fe2O3 in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe2O3 becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe2O3 and the decreased peak strength of Ag/α-Fe2O3. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe2O3 when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe2O3 is stronger than that of Ag-doped α-Fe2O3.

Physical properties of chalcopyrite-type Cu1−xAgxGaTe2 by first-principles study

2016 ◽  
Vol 30 (30) ◽  
pp. 1650373 ◽  
Author(s):  
Li Xue ◽  
Yi-Ming Ren ◽  
Zheng-Long Hu
Keyword(s):  
Thermal Conductivity ◽  
Elastic Constants ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Lattice Parameter ◽  
Functional Theory ◽  
Lattice Volume ◽  
Te Material ◽  
Ag Substitution ◽  
Good Agreement

[Formula: see text] is a promising thermoelectric (TE) material for high temperature TE applications. This work systematically investigated the structural, elastic and thermodynamic properties of [Formula: see text] ([Formula: see text] = 0, 0.25, 0.5, 0.75 and 1) by density functional theory. The calculated lattice volume is expanded with the increase of Ag content, but this expansion is anisotropic. The lattice parameter along [Formula: see text]-axis is linear expansion, and along [Formula: see text]-axis is parabolic expansion, which is in good agreement with available experimental data. The phase stability of [Formula: see text] alloy is studied by analyzing the formation energy, cohesive energy and elastic constants. Shear modulus, Young’s modulus, sound velocities, Debye temperature and the minimum thermal conductivity are obtained from the calculated elastic constants. The results show that Ag substitution could reduce the lattice thermal conductivity, which is helpful for improving the TE properties of [Formula: see text].

Research Optical Characteristics of H2S Molecule Adsorption on Agn (n=2,4,6) Clusters

2013 ◽  
Vol 321-324 ◽  
pp. 499-502
Author(s):  
Hong Zhou ◽  
Jun Feng Wang ◽  
Jun Qing Wen ◽  
Wei Bin Cheng ◽  
Jun Fei Wang
Keyword(s):  
Density Functional Theory ◽  
Infrared Spectrum ◽  
Density Functional ◽  
Global Minimum ◽  
Electronic States ◽  
Binding Energies ◽  
Optical Characteristics ◽  
Functional Theory ◽  
Calculation Results ◽  
Planar Geometries

Density-functional theory has been used to calculate the energetically global-minimum geometries and electronic states of AgnH2S (n=2, 4, 6) clusters. The lowest-energy structures of Ag2, Ag4, Ag6, Ag2H2S, Ag4H2S and Ag6H2S clusters were obtained, respectively. The calculation results show that the lowest-energy structures of Ag2, Ag4and Ag6clusters are planar geometries. The binding energies of Agn(n=2, 4, 6) clusters are gradually increasing in our calculations. Compare the infrared spectrum peaks of Ag4cluster with that of Ag6cluster, which show that the peaks shift to shortwave. After adsorption, we found that the peaks shift to shortwave by comparison.

scholarly journals Effect of Point Defects on Electronic Properties and Structure of Talc (001) Surface by First Principles

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 69
Author(s):  
Xindi Ma ◽  
Huicong Du ◽  
Ping Lan ◽  
Jianhua Chen ◽  
Lihong Lan
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Surface States ◽  
State Density ◽  
Functional Theory ◽  
Vacancy Defects ◽  
Impurity Atoms ◽  
Electron State Density ◽  
Calculation Results ◽  
Impurity Defects

The surface structure and electronic properties of Mg vacancy defects on talc (001) and impurity defects with Fe, Mn, Ni, Al, and Ca replacing Mg atoms were calculated by using density functional theory. The calculation results show that the order of impurity substitution energy is Mn < Ni < Al < Ca < Fe. This indicates that Fe impurity defects are most easily formed in talc crystals. The covalent bonding between Si atoms and reactive oxygen atoms adjacent to impurity atoms is weakened and the ionic property is enhanced. The addition of Fe, Mn, and Ni atoms makes the surface of talc change from an insulator to a semiconductor and enhances its electrical conductivity. The analysis of electron state density shows that surface states composed of impurity atoms 4S orbital appear near the Fermi level.

Theoretical Research on Structure and Infrared Spectra of the 9-Methacrylate Carbazole Molecule

2022 ◽  
Vol 905 ◽  
pp. 117-121
Author(s):  
Hui Li ◽  
Bing Guo ◽  
Kun Wang ◽  
Ming Yu Zhou
Keyword(s):  
Infrared Spectrum ◽  
Density Functional ◽  
Spatial Configuration ◽  
Density Functional Theory Method ◽  
Peak Position ◽  
Theoretical Research ◽  
Imaginary Frequency ◽  
Functional Theory ◽  
Calculation Results ◽  
Base Group

Using the quantum chemical density functional theory method in the Gaussian03W package, the spatial configuration of this compound is optimized by using B3LYP/6-31G(d) as the base group, in which the data of bond length, bond angle and spatial dihedral angle of the compound molecule are obtained. Based on the optimized stable structure, the infrared vibration frequency of the molecule is calculated, and the infrared spectrum is drawn. There is no imaginary frequency in the calculation results of frequency value, which indicates that the optimized configuration of 9-methacryloyl carbazole molecule is reasonable, and the peak position of infrared spectrum is assigned.

Bisoxazoline–copper(I)-catalyzed aziridination of diazoacetate with imines — A DFT study

2010 ◽  
Vol 88 (10) ◽  
pp. 981-990 ◽  
Author(s):  
Qingxi Meng ◽  
Fen Wang ◽  
Ming Li
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Mode I ◽  
Mode Ii ◽  
Free Energies ◽  
Functional Theory ◽  
Carboxylate Complex ◽  
Calculation Results ◽  
Favorable Reaction ◽  
Level Calculation

Density functional theory (DFT) has been used to study bisoxazoline–copper(I)-catalyzed aziridination of diazoacetate with syn-imines or anti-imines. All the intermediates and transition states were optimized completely at the B3LYP/6-31G(d) level. Calculation results confirm that Cu(I)-catalyzed aziridination goes mainly through the catalyst–diazoacetate complex (M1), the copper(I)–carbene intermediate (M2), the copper–carbene–imine complex (M3), and the catalyst–aziridine carboxylate complex (M4). For syn-imines, the reaction mode I (C3–N5 bond attacking the Cu–C1 bond of M2) is more dominant than the reaction mode II (C3–N5 bond attacking the carbene–carbon C1 of M2), and the attack from the si-surface of M2 is prior to the re-surface. For anti-imines, the reaction modes and attacks from the si- or re-surface coexist. The reactivity of syn-imines is stronger than anti-imines. The favorable reaction channel is CA2 → M1b → TS1b → M2 → syn-TS2b → syn-M3b → syn-TS3b → syn-M4b → syn-P2. The dominant product theoretically predicted is of (S,S)-chirality. On the whole, the solvent effect decreases the free energies of the species.

Hydration of a sulfuric acid–oxalic acid complex: acid dissociation and its atmospheric implication

RSC Advances ◽  
2015 ◽  
Vol 5 (60) ◽  
pp. 48638-48646 ◽  
Author(s):  
Shou-Kui Miao ◽  
Shuai Jiang ◽  
Jiao Chen ◽  
Yan Ma ◽  
Yu-Peng Zhu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Sulfuric Acid ◽  
Oxalic Acid ◽  
Density Functional ◽  
Structural Characteristics ◽  
Acid Dissociation ◽  
Acid Complex ◽  
Functional Theory ◽  
Insight Into

We have investigated structural characteristics and thermodynamics of the hydration of a sulfuric acid–oxalic acid complex using density functional theory to gain insight into the ternary nucleation and its atmospheric implication.

Study on Electronic and Optical Properties of Al-Doped ZnS from Density Function Theory

2013 ◽  
Vol 734-737 ◽  
pp. 2405-2410 ◽  
Author(s):  
Ai Ling Wu ◽  
Li Guan ◽  
Ting Kun Gu ◽  
Pei Yuan Feng
Keyword(s):  
Optical Properties ◽  
Absorption Spectra ◽  
Density Functional ◽  
Systematic Investigation ◽  
Al Doping ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Calculation Results ◽  
Plane Wave Approximation ◽  
Good Agreement

Using ab-initio ultrasoft pseudopotential plane wave approximation method based on density functional theory (DFT), a systematic investigation on electronic and optical properties of ZnS with and without Al-doping has been performed. Calculation results show that Al-doping narrows the band gap of ZnS systems and Al-doped ZnS system changes from semiconductor into metal through the Mott transition. Moreover, with Al-doping increasing, the increase of absorption coefficient and redshift of absorption spectra are obtained. Absorption spectra of pure ZnS and Al-doped ZnS are in good agreement with the experimental results.

scholarly journals The Interaction of Air Pollutant Molecules with Germanene and Silicene: a Density Functional Theory Study

Molekul ◽  
2018 ◽  
Vol 13 (1) ◽  
pp. 92
Author(s):  
Muhammad Rifqi Al Fauzan ◽  
Wijayanti Dwi Astuti ◽  
Ghorby Al Fauzan ◽  
Sholihun Sholihun
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Adsorption Process ◽  
Air Pollutant ◽  
Atmospheric Pollutants ◽  
Mulliken Charge ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Calculation Results ◽  
Adsorbent Materials

We investigate the adsorption of atmospheric pollutants on germanene and silicene using density functional theory (DFT) calculations. In this study, we use carbon monoxide (CO) and nitric oxide (NO) as the pollutant molecules. Electronic properties of germanene and silicene are explored to obtain a good understanding in the adsorption process. Our calculation results show both germanene and silicene provide an identical mechanism of adsorption. Germanene and silicene adsorb CO and NO spontaneously with physisorption and chemisorption types for CO and NO molecules, respectively. We also conduct the Mulliken charges calculations to evaluate the transformation of atomic charges due to the adsorption process. From Mulliken charge calculation results we can confirm the existence of charge transfer between the adsorbent materials and the pollutant molecules. This phenomenon lies behind the occurrence of the adsorption process.

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