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The current study presents superposition‐based concurrent multiscale approaches for porodynamics, capable of capturing related physical phenomena, such as soil liquefaction and dynamic hydraulic fracture branching, across different spatial length scales. Two scenarios are considered: superposition of finite element discretizations with varying mesh densities, and superposition of peridynamics (PD) and finite element method (FEM) to handle discontinuities like strain localization and cracks. The approach decomposes the acceleration and the rate of change in pore water pressure into subdomain solutions approximated by different models, allowing high‐fidelity models to be used locally in regions of interest, such as crack tips or shear bands, without neglecting the far‐field influence represented by low‐fidelity models. The coupled stiffness, mass, compressibility, permeability, and damping matrices were derived based on the superposition‐based current multiscale framework. The proposed FEM‐FEM porodynamic coupling approach was validated against analytical or numerical solutions for one‐ and two‐dimensional dynamic consolidation problems. The PD‐FEM porodynamic coupling model was applied to scenarios like soil liquefaction‐induced shear strain accumulation near a low‐permeability interlayer in a layered deposit and dynamic hydraulic fracturing branching. It has been shown that the coupled porodynamic model offers modeling flexibility and efficiency by taking advantage of FEM in modeling complex domains and the PD ability to resolve discontinuities. [ABSTRACT FROM AUTHOR]

The current study presents superposition‐based concurrent multiscale approaches for porodynamics, capable of capturing related physical phenomena, such as soil liquefaction and dynamic hydraulic fracture branching, across different spatial length scales. Two scenarios are considered: superposition of finite element discretizations with varying mesh densities, and superposition of peridynamics (PD) and finite element method (FEM) to handle discontinuities like strain localization and cracks. The approach decomposes the acceleration and the rate of change in pore water pressure into subdomain solutions approximated by different models, allowing high‐fidelity models to be used locally in regions of interest, such as crack tips or shear bands, without neglecting the far‐field influence represented by low‐fidelity models. The coupled stiffness, mass, compressibility, permeability, and damping matrices were derived based on the superposition‐based current multiscale framework. The proposed FEM‐FEM porodynamic coupling approach was validated against analytical or numerical solutions for one‐ and two‐dimensional dynamic consolidation problems. The PD‐FEM porodynamic coupling model was applied to scenarios like soil liquefaction‐induced shear strain accumulation near a low‐permeability interlayer in a layered deposit and dynamic hydraulic fracturing branching. It has been shown that the coupled porodynamic model offers modeling flexibility and efficiency by taking advantage of FEM in modeling complex domains and the PD ability to resolve discontinuities. [ABSTRACT FROM AUTHOR]

Topological flatband materials have garnered significant attention due to their strongly correlated electronic states. Here, we propose the typical flatband and topological features in the classical copper-based kagome lattice CaCu 5. Our work confirms the stability of the CaCu 5 system. Notably, we identify flatbands in the band structure of the CaCu 5 system, accompanied by a typical quadratic band with line touching, and the flatness of flatbands is broken when spin–orbit coupling is introduced. Furthermore, parity and symmetry eigenvalue calculations of the wavefunctions reveal the nontrivial topological properties of the system. Our results suggest that the CaCu 5 system, with its topological flatbands, serves as an ideal platform for studying strong correlation effects and novel physical phenomena. [ABSTRACT FROM AUTHOR]

The enhancement of horizontal boundaries of potential field sources is of great significance for the study of geological structures. Most of the existing filters for horizontal edges enhancement are presented based on the derivatives of potential field data, but these filters often show some shortcomings, for example, the output edges are divergent, strong and weak anomalies cannot be balanced, or some extra false edges appear in the results. In this paper, the edges enhancement filter MMA based on mathematical morphology is first defined by the combination of the basic operators of mathematical morphology. In order to make the filter have the ability to balance different amplitude anomalies, MMAZ and MMAT are proposed, and both of them can be used to delineate the horizontal edges of the field sources by their maxima. The experimental results of synthetic data show that MMAZ and MMAT have good equalization and anti-noise performances. Compared with several traditional filters, the horizontal edges of geological bodies obtained by these two filters are clearer and more convergent, and there are no extra edges in the output results for the complex situations that positive and negative anomalies exist simultaneously. Finally, the two new equalization filters are applied to gravity anomaly data in a potash mine area in Vientiane basin of Laos and the aeromagnetic anomaly of a metal mine in northwest China, the obtained positions of the structures are more accurate and clearer, which further illustrates the effectiveness of the two filtering techniques. [ABSTRACT FROM AUTHOR]

High-temperature ferromagnetism has always been a classic and interesting subject, especially in spin gapless semiconductor PbPdO 2 with exotic properties. Here, a combination of theoretical and experimental studies was employed to clarify the origin of high Tc. First, based on first-principles calculations, electronic band structures of PbPd 0.875 Co 0.125 O 2 at different Co substitution positions were studied. Our results indicate that Co atoms tend to form an antiferromagnetic ground state due to the Co–O–Co (180 °) indirect exchange effect, while ferromagnetism is favored in Co-doped PbPdO 2 when a unique molecular field effect induced band crossover and p – d coupling occurs. It is revealed that metallic or semiconductor properties have an important connection with ferromagnetism or antiferromagnetism. Subsequently, a Monte Carlo simulation was carried out based on the first-principles results to predict the ferromagnetism of PbPd 0.875 Co 0.125 O 2. Finally, the moment-magnetic field and moment-temperature curves were also measured for PbPd 0.875 Co 0.125 O 2 samples, which was found well consistent with the theoretical findings. The ground state of PbPd 0.875 Co 0.125 O 2 was confirmed to be ferromagnetic. Our results well explain the origin of high-temperature ferromagnetism in diluted magnetic semiconductors and provide new approaches for the design of future high Tc spintronic devices. [ABSTRACT FROM AUTHOR]

HLA‐C*03:652 differs from the HLA‐C*03:04:01:01 by one nucleotide in exon 3. [ABSTRACT FROM AUTHOR]

• Sol-gel method was used for the synthesis of pristine, cerium and vanadium doped nio-nps. • White egg yolks was used as a stabilizing agent for the synthesis of NiO NPs. • The UV–VIS analysis shows that band gap decreased 3.52 to 3.30 eV with doping agent. • It was observe that resistivity decreased of doped NiO–NPs and conductivity increased. • Seebeck coefficient was increased by increasing temperature upto significant level of v doped NiO NPs. To investigate the optical, electrical and thermoelectric properties of pristine, cerium and vanadium doped NiO NPs was synthesized by using sol-gel method. The XRD was used to investigate the FCC cubic crystal structure and crystallite size decreased from 75 to 43 nm. However, SEM micrographs depicted irregular surface morphology changed into small agglomerated grains by vanadium doped NiO–NPs. After that the EDAX analysis was performed to obtain the elemental composition (Ni, O, Ce and V) and also identified the weight percent of each element in all samples. The different functional groups such as Ni O, OH, C O, CO 2 , C C and V O was examined by FTIR spectra. The absorbance peak of pristine and doped NiO NPs indicate the blue shift and band gap decreased from 3.52 to 3.30 eV was calculated by UV-VIS analysis. The electrical properties were examined with two probe method and draw the relation between resistivity and conductivity. It was observed that the resistivity decreased (6 × 103 to 2 × 103 ohm-cm) with Ce and V doped NiO NPs and conductivity increased (2 × 10–5 to 6 × 10–3 S/cm). Further, seebeck coefficient was calculated with the help of thermoelectric analysis and it was observed that seebeck coefficient increased by increasing temperature upto significant level. Overall analyses shows that vanadium doped NiO NPs are excellent candidate for optical, electrical and thermoelectric measurements. While as prepared cerium and vanadium doped NiO NPs will be helpful of electrical and thermoelectric devices. [ABSTRACT FROM AUTHOR]

The shape of particles can have a great impact on the mechanical behavior of granular material, which is not only limited to general shape measures such as sphericity and roundness, but also applies for small scale measures such as surface asperities. In this study, triaxial tests on 3D printed particles and DEM tests show that small surface asperities on spherical particles can contribute significantly to the peak strength and dilatancy of granular material, which cannot be reflected by simply altering the traditional contact parameters in DEM. Using polydispersed particles with artificially designed surface asperities in the form of bumps for laboratory and DEM triaxial tests, both macro and micro scale behavior of granular material are analyzed to reveal the influence of these small surface asperities. The result shows that surface asperities can change the coordination number, anisotropy, and normal contact force on the micro scale, increasing the interlocking between particles and restricting particle rotation, which leads to the increase of peak strength and dilatancy on the macro scale. Although the commonly adopted approach of introducing rolling resistance to reflect shape influence can help to enhance the simulation of stress‐strain relationship, especially for particles with relatively small artificial asperities, the micro scale influence of rolling resistance and surface asperities are found to be different as the size of the asperities increase. [ABSTRACT FROM AUTHOR]

Liquefaction-induced shear strain localisation and delayed failure occur when a low-permeability overlying soil layer impedes the dissipation of excess pore water pressure generated by the underlying sand. When this phenomenon is simulated by the classical finite-element method (FEM), the predicted strain localisation and lateral deformation are mesh-size dependent. In this study, the non-local peridynamics theory is introduced as a novel regularisation technique for modelling such a phenomenon. The computational model is based on coupling the non-ordinary state-based peridynamics (NOSBPD) and FEM for the solid and pore fluid phases, respectively. The liquefiable sand is modelled using a plastic model for large post-liquefaction shear deformation of sand (CycLiq) in the NOSBPD layer and the fluid flow is solved in the FEM layer. After validation of the proposed method using a VELACS centrifuge model test, the seismic response of an idealised one-dimensional sloping site with a low-permeability interlayer is analysed using various discretisation resolutions. The results show that the proposed method for liquefaction-induced strain localisation analysis is insensitive to spatial discretisation density. Finally, the Lower San Fernando dam failure case is revisited. The localised sliding and delayed failure of the dam observed in the field is achieved in the simulation. The results demonstrate the potential of the proposed method in assessing realistic cases associated with liquefaction-induced shear strain localisation. [ABSTRACT FROM AUTHOR]

An explicit material point and finite volume sequentially coupled method (MPM-FVM) is developed using u - p form coupling formulations for the simulation of large deformations in saturated soil. In MPM-FVM, the momentum conservation equation is solved by MPM under the updated Lagrange framework, and the mass conservation equations are solved by FVM under the Euler framework. The numerical implementation of an explicit sequentially coupled algorithm is developed considering the tradeoffs between computational cost and numerical stability. The critical time step of u - p form governing equations is derived using the Von Neumann method, which is found to be much greater than the u - U form explicit MPM at low permeability, allowing for high numerical stability. Three numerical cases are presented to demonstrate the stability, efficiency, and effectiveness of the developed MPM-FVM method. The simulation of a saturated one-dimensional soil column subjected to quasi-static and dynamic loads validates the method, and highlights its greater efficiency and accuracy compared to standard solid–fluid coupled MPM methods. The large deformation simulation capability of the method is exhibited via simulation of a saturated slumping block. In real-world application, simulation results obtained using method achieves excellent agreement with the experiment measurements and observations of the Selborne landslide experiment. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, thermodynamic, and mechanical properties of the hypothetical quaternary Heusler alloys (QHAs) TiHfIrZ (Z = Al, Ga, In) have been investigated by first-principles calculations within generalized gradient approximation (GGA) method. Since the QHAs TiHfIrZ (Z = Al, Ga, In) are not studied experimentally and theoretically so far, we first research that the most stable configurations of the QHAs TiHfIrZ (Z = Al, Ga, In) are all Y-type (I) in ferromagnetic (FM) phase. The large absolute values of both negative formation energy and positive cohesion energy verify the thermodynamic stabilities of the QHAs TiHfIrZ (Z = Al, Ga, In). The higher than the room-temperature Curie temperatures TC, as large as 2 μB/f.u total magnetic moments per formula unit and the half-metallic (HM) characters, indicate the QHAs TiHfIrZ (Z = Al, Ga, In) can be used in the magnetoelectronics and spintronics fields. The QHAs TiHfIrZ (Z = Al, Ga, In) have mechanical stabilities, ductility, and high hardness. The lattice constant regions of maintaining the HM characters are 5.722–6.405 Å, 5.786–6.402 Å, and 5.839–6.589 Å for QHAs TiHfIrZ (Z = Al, Ga, In), respectively. [ABSTRACT FROM AUTHOR]

The effects of various vacancies and group‐VIB and VIIB transition metal substitutional doping on the structural, electronic, and magnetic properties of monolayer HfS2 are studied by first‐principles calculations. The results show that pristine monolayer HfS2 is a nonmagnetic semiconductor; it becomes a metal on creating a single V1Hf or V1S vacancy, whereas it is still a semiconductor on creating V1Hf+1S divacancy or V1Hf+2S trivacancy. The V1Hf single vacancy and V1Hf+1S divacancy induce magnetic moments of 3.265 and 2.000 μB, respectively, whereas the V1S single vacancy and V1Hf+2S trivacancy do not induce any magnetic moments. One of the group‐VIB and VIIB transition metal atoms substituting for one Hf atom in the monolayer HfS2 induces magnetic moments of about 2.000 and 3.000 μB, respectively. Furthermore, the spin‐polarized band structures show that the Cr‐doped monolayer HfS2 is a magnetic metal, whereas the Mn‐, Tc‐, and Re‐doped monolayer HfS2 are magnetic semiconductor. The Mo‐ and W‐doped monolayer HfS2 are magnetic half metal with wide spin‐down bandgaps of 0.975 and 1.074 eV, respectively, and thus can be used in nanoelectronics and spintronics devices. [ABSTRACT FROM AUTHOR]

The structural, electronic and optical properties in bulk and (100) as well as (110) surfaces of full-Heusler alloys X2CoGa (X = Ti, Hf) have been investigated by spin-polarized first-principles calculations. In spin-down channel of bulk X2CoGa (X = Ti, Hf) alloys, the conduction band minimum is contributed by XA-3d(t2g) and XB-3d(t2g), while the valence band maximum is contributed by XB-3d(t2g) and Co-3d(t2g) states. For bulk X2CoGa (X = Ti, Hf) alloys, the peak values of real part ε 1 (ω) and imaginary part ε 2 (ω) of dielectric constant ε (ω) , refractive index n (ω) , extinction coefficient k (ω) and absorption coefficient α (ω) , all present the blue shift characteristics with decreasing lattice constant induced by increasing pressure. The ideal TiGa (HfGa) termination of Ti2CoGa (Hf2CoGa) (100) surface and TiCoGa termination of Ti2CoGa (110) surface with the much lower surface energies have higher spin-polarizations of 97.9% (84.9%) and 94.0%, respectively, but the Ti2CoGa alloy has the superiority using for spintronic devices compared to the Hf2CoGa alloy in thin film form. Compared to the Hf2CoGa alloy, the ideal TiCoGa termination of Ti2CoGa (110) surface with much superiority optical property has the largest absorption coefficient α (ω) along c axis at about 7.5 eV and the α (ω) is almost zero when the energy is larger than 22.5 eV in all the six surface cases which is much different from the bulk alloy case. [ABSTRACT FROM AUTHOR]

In order to meet the user's increasing demands for integrated quality of agricultural machinery products, a new KE-TRIZ approach based on Kansei engineering (KE) and theory of inventive problem solving (TRIZ) was proposed. Designers used semantic difference (SD) method and principal component analysis (PCA) method to quantify and reduce the dimensions of the extracted perceptual vocabulary, which aimed to select the comprehensive variables that represented the user's needs. TRIZ theory was used in the product emotional intention to elaborate the invention principle of products' appearance structure and functional technology, and improvement explanation was put forward based on further contradiction analysis. Then, the industrial design theory was combined with the innovation design of agricultural machinery products. In order to explain the reliability of innovative design, the analytic hierarchy process (AHP) was used in objective assessment. Finally, a walking rotary cultivator design was used as a case to check the above methods. The research can effectively adjust the contradiction between rationality and sensibility in products and apply it to the product equipment with function as the main part to design the products of comprehensive quality that conform to the trend of social aesthetics so as to form the brand effect of high added value. The results showed that these methods were effective and feasible for the innovative design of agricultural machinery products. [ABSTRACT FROM AUTHOR]

• (0 0 2) preferred orientation PbPdO 2 film can be well fabricated using PLD method. • Cu1+, Co2+,3+ and Fe3+ are identified in the doped PbPdO 2 thin films. • Pb(Pd,M)O 2 (M = Cu, Co, Fe) films exhibit ferromagnetism with TMI at around 330–370 K. • Fe doping can greatly enhance the electrical resistivity and magnetism. • Based on Pb vacancy and O−1, the band gap and magnetic moment are explained well. PbPdO 2 and M-doped PbPdO 2 (M = Cu, Co, Fe) films were prepared using pulsed laser deposition (PLD) method. The structures, electrical and magnetic properties were systematically investigated by XRD, Raman, SEM, XPS, AFM and VSM. Our results indicate that PbPdO 2 and PbPd 0.9 M 0.1 O 2 (M = Cu, Co, Fe) film with (0 0 2) preferred orientation can be well fabricated. The valence states of magnetic atoms in M-doped PbPdO 2 (M = Cu, Co, Fe) thin films are identified to be Cu1+, Co2+,3+ and Fe3+, respectively. All Pb(Pd,M)O 2 (M = Cu, Co, Fe) films exhibit ferromagnetism with high metal-insulator transition temperatures at around 330–370 K. Moreover, the resistivity of Fe doped PbPdO 2 film is higher than that of the pristine PbPdO 2 film, while the resistivities of Co and Cu doped PbPdO 2 films are lower. At the same time, Fe, Co and Cu dopants do enhance the ferromagnetism of PbPdO 2 film, while the enhancement of magnetic moment for Fe dopant is most evident. Lastly, based on Pb vacancy and O−1 observed experimentally, the band gaps and magnetic moments of Pb(Pd,M)O 2 films were calculated by first-principles, and the results explain well the experimental facts. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • PANI/C-ACs were synthesized by an economical in-situ polymerization method. • PANI nanorods uniformly grew onto C-ACs skeletons forming a 3D porous structure. • PANI/C-ACs exhibit good capacitive properties by synergistically reinforcing effect. Abstract Polyaniline/cellulous-derived highly porous activated carbons (PANI/C-ACs) composites have been synthesized for high-performance supercapacitors via a simple and economical method. The obtained three-dimensional and hierarchical porous structure of PANI/C-ACs, not only exhibited high specific surface area and electron conductivity, but also promoted electrolyte ion transportation, facilitated fast and stable surface redox reactions, hence synergistically improved the overall capacitive performance. The as-designed PANI/C-ACs composites exhibited a specific capacitance of 765 F/g at 1 A/g and capacitance retention of two-electrode cell was as high as 91% after 5000 cycles. Moreover, evident pseudocapacitive behavior can be well maintained at high current densities, indicating superior rate capability for these hierarchically structured composites, making them promising electrode materials for high performance supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we modify the magnetic and electronic properties of zigzag boron nitride nanoribbons (ZBNNRs) with asymmetric edge passivation nonmetallic (NM) atoms. The 12 possible cases of the XN-ZBNNR-BY systems (X, Y=O, S, F or P) can be divided into four types: the PN-ZBNNR-BY (Y=O, S or F), SN-ZBNNR-BY (Y=F, O or P), ON-ZBNNR-BY (Y=F, S or P) and FN-ZBNNR-BY (Y=O, P or S). The results show that all four types of the XN-ZBNNR-BY systems display the metallic properties in both channels mainly due to termination atoms O, S and P with 4, 4 and 3 p electrons, but only the ON-ZBNNR-BY (Y=F, S or P) systems display the magnetic properties. Furthermore, the total magnetic moments of the ON-ZBNNR-BY (Y=F, S or P) systems are contributed constantly by the termination O atoms and edge N atoms, regardless of termination Y atoms. Finally, the contributions to the total magnetic moments are very small for the inner N and B atoms. Graphical abstract The geometrical structural model of nonmetallic atom terminated ZBNNRs, XN-ZBNNR-BY (X, Y=O, S, P or F). The yellow, grey, green and red balls represent X, N, B and Y atoms, respectively. X and Y stand for different nonmetallic atoms. Image 1 Highlights • Magnetic and electronic properties of the XN-ZBNNR-BY (X, Y=O, S, F or P) are studied. • All XN-ZBNNR-BY systems display metal properties in both channels due to termination O, S and P atoms. • Only ON-ZBNNR-BY (Y=F, S or P) system has magnetic properties due to termination O and edge N atoms. • Contributions to the total magnetic moments are very small for the inner N and B atoms. [ABSTRACT FROM AUTHOR]

Fabric influences the macro scale mechanical properties and behavior of granular materials as a continuum and can be represented by an appropriately defined evolving fabric tensor entering the constitutive equations. In this study, the evolution of fabric tensors under cyclic loading is investigated and quantified by a series of cyclic loading DEM tests. Simulations of the DEM data are made by two different continuum evolution rate equations for the contact normal‐based fabric tensor, both within the Anisotropic Critical State Theory (ACST) framework: the first, is a Basic Fabric Evolution (BFE) equation and the second, is a novel Combined Fabric Evolution (CFE) equation, where a quantity related to particle‐based fabric tensor is considered. The comparison with DEM results highlights the capability of the CFE equation in simulating fabric evolution under cyclic loading for different anisotropy, density, and loading conditions. In addition, such simulations are significantly more accurate in comparison with those obtained by the BFE equation. The reason for the superiority of CFE over the BFE is the incorporation of the influence of the particle orientation fabric on contact normal fabric evolution. Analytical evaluation of CFE further identifies a total of seven periodic stable contact normal fabric evolution patterns that exist under cyclic loading, governed by initial void ratio, intensity of anisotropy, and stress amplitude. The limitation of current fabric evolution equations in being able to only reflect the proportional coaxial part of the fabric tensor with respect to the loading direction is discussed. [ABSTRACT FROM AUTHOR]

Abstract The effects of the pressure on the structural, electronic, magnetic and optical properties of the Zn 0.75 V 0.25 Te alloy have been investigated by density functional calculations. The ductile characteristic and the half-metallic feature of Zn 0.75 V 0.25 Te alloy under pressure are found. The band structures with a color scale indicating the contribution weights from V and Te + Zn atoms show that V element is dominant in the spin-up channel crossing the Fermi level but there is a band gap in the spin-down channel. The half-metallic feature of the Zn 0.75 V 0.25 Te alloy can be observed under the pressures of 0–4 GPa. It is discovered that the total moment of 3 μ B /cell is contributed by the three 3d-electrons of V2 + ion. With increasing pressure, the spin-down band gap E g increases, while the static dielectric function ε 1 (0) and static refractive index n (0) decrease, the peaks of the real part ε 1 (ω) and imaginary part ε 2 (ω) of the dielectric constant, the refractive index n (ω) , the extinction coefficient k (ω) and absorption coefficient α (ω) all show the blue shift character. The results provide useful theoretical guidance for the application of the Zn 0.75 V 0.25 Te alloy in optical detectors and spintronics devices under pressure. Graphical abstract Image Highlights • The half-metallic feature of the Zn 0.75 V 0.25 Te under pressure is found. • The V element is dominant in the spin-up channel crossing the Fermi level. • The 3 μ B /cell total moment is contributed by the three 3d electrons of V2+ ion. • With increasing pressure, the E g increases, while ε 1 (0) and n (0) decrease. • The peaks of ε 1 (ω) , ε 2 (ω) , n (ω) , k (ω) and α (ω) all have blue shift character under pressure. [ABSTRACT FROM AUTHOR]

Abstract In this study, the structural and electronic properties of CoX 0.25 S 1.75 (X = F, Cl, or Br) were investigated based on spin-polarized first-principles calculations. S-F, S-Cl, and S-Br covalent bonds are not present in CoX 0.25 S 1.75 (X = F, Cl, or Br). The generalized gradient approximation (GGA) + U and Heyd-Scuseria-Ernzerhof hybrid functional method may overestimate the spin-down band gap for CoS 2. The results obtained for CoX 0.25 S 1.75 (X = F, Cl, or Br) using the GGA method are expected to be more reasonable. Only the half-metal CoF 0.25 S 1.75 can be used for spintronic applications and the metal CoX 0.25 S 1.75 (X = Cl or Br) is more suitable for use in supercapacitors. The p - d hybridization between S and Co atoms in CoF 0.25 S 1.75 is stronger compared with that in CoS 2. The p - d hybridization between S(S-X) and Co atoms is stronger whereas that between S(S-S) and Co atoms is weaker in CoX 0.25 S 1.75 (X = Cl or Br). Doping with F and Cl (Br) atoms in CoS 2 induces new bands with less and more dispersion, respectively. In CoX 0.25 S 1.75 (X = F or Cl), X atoms gain more electrons than S atoms and the charge density difference indicates that S atoms donate electrons to F and Cl atoms. However, in CoBr 0.25 S 1.75 , Br atoms gain fewer electrons than S atoms and there is almost no charge transfer between S and Br atoms. Graphical abstract Image 1 Highlights • Results obtained for CoX 0.25 S 1.75 by GGA method are expected to be more reasonable. • CoF 0.25 S 1.75 is half–metallic and can be used for spintronic applications. • CoCl 0.25 S 1.75 and CoBr 0.25 S 1.75 are more suitable for use in supercapacitors. • Doping CoS 2 with F/Cl (Br) atoms induced new bands with less/more dispersion. [ABSTRACT FROM AUTHOR]

The electronic, magnetic and optical properties of Co doped marcasite FeS 2 compounds have been investigated through the first-principles calculations. No imaginary frequency emerges in the phonon dispersion curves confirms the Fe 7 CoS 16 and Fe 6 Co 2 S 16 compounds are dynamical stable. Although the pure Fe 8 S 16 compound is a nonmagnetic semiconductor with band gap of 1.17 eV, the Fe 7 CoS 16 compound changes to a magnetic semiconductor with a very narrow band gap of 0.106 eV, the Fe 6 Co 2 S 16 compound changes to a half-metal with half-metal band gap of 0.37 eV in spin-down channel. For all three considered configurations of the Fe 6 Co 2 S 16 compound, the ferromagnetic state is preferred over antiferromagnetic state, especially for smaller separation distance of two doped Co atoms. The higher Curie temperatures than room temperature indicates the Fe 6 Co 2 S 16 compound is a promising candidate for spintronics applications. In addition, the calculated optical properties shows that Fe 7 CoS 16 and Fe 6 Co 2 S 16 compounds have stronger absorption than Fe 8 S 16 compound when the wavelength more than 500 nm, which suggests the compounds are potential candidates for solar cells. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we modify the magnetic and electronic properties of zigzag boron nitride nanoribbons (ZBNNRs) by adopting the method of edge-modification, which is achieved by passivating the edges of ZBNNRs with nonmetallic (NM) atoms H, O, S, F and P. Five different cases for XN + N-ZBNNR-B + BH, where X = H, O, S, F and P nonmetallic (NM) atoms are studied systematically. The calculated results indicate that for only X = P, the XN + N-ZBNNR-B + BH displays the half-metallic feature while the others exhibit metallic properties. The metallic feature of the XN + N-ZBNNR-B + BH (X = H, O, S, and F) systems is due to the contribution of both termination atoms and edge atoms to the total density of states at the Fermi level. The XN + N-ZBNNR-B + BH (X = H, O, S, F and P) are all magnetic materials. In addition, the half-metallic feature of the PN + N-ZBNNR-B + BH material is a new style of nano-material and a perfect candidate for spintronic applications. Graphical abstract The total density of states (TDOS) and atom-projected density of states (PDOS) of PN + N-ZBNNR-B + BH, (a) Total DOS, (b) PDOS of terminated atoms P and H, (c) PDOS of edge passivated and bare N atoms, and (d) PDOS of edge passivated and bare B atoms. The positive and negative values represent the spin-up and spin-down channels, respectively. The Fermi level E F is set at zero energy and indicated by the vertical red dashed line. Image 1 Highlights • Structural, magnetic and electronic properties of XN + N-ZBNNR-B + BH (X = H, O, S, F or P) are studied. • Total magnetic moments of the systems are mainly contributed by edge atoms and terminated atoms. • Only PN + N-ZBNNR-B + BH shows half-metallic feature, the other systems display metallic properties. • For X = O or S cases, the edge states located near the E F are produced by the terminated atoms O or S. • For X = F or H cases, the edge states located far away from E F are produced by termination atoms F or H. [ABSTRACT FROM AUTHOR]

A new type of self‐reinforced composite based on high‐performance aramid fibers was developed to produce an "all‐aramid" composite by applying a surface‐dissolution method to fuse poly(p‐phenyleneterephthalamide) (PPTA) fibers together. After immersion in concentrated (95%) sulphuric acid (H2SO4) for a selected period of time, partially dissolved fiber surfaces are converted into a PPTA matrix phase. Following extraction of sulphuric acid and drying, a consolidated composite structure is formed. By examining the microstructure and mechanical properties of all‐aramid composites, it was found in our previous study that the optimal immersion time of aramid fibers in 95% sulphuric acid was 120 s. In this article, other processing variables—including initial and final coagulation, coagulation time, consolidation pressure, and time—were regulated and their effects on the morphology, mechanical properties and, crystallization of all‐aramid composites were investigated and discussed. A series of optimal surface‐dissolution processing conditions were achieved to obtain the best‐achievable microstructure and mechanical properties of all‐aramid composites. All‐aramid composites prepared with these optimum conditions possess excellent mechanical properties along the direction of orientation with tensile strength of 1.44 GPa and tensile modulus of 76.8 GPa. As fiber, matrix, and interphase in all‐aramid composites are based on the same high‐temperature‐resistant PPTA polymer, these materials have the prospective potential for high‐temperature applications. POLYM. COMPOS., 39:3307–3316, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A new self‐reinforced polymer composite based on high‐performance aramid fibers was successfully prepared by applying an elaborately designed surface‐dissolution method to fuse poly(p‐phenylene terephthalamide) (PPTA) fibers and consolidate them into "all‐aramid" composites. A mixture of phosphoric acid (H3PO4) and sulfuric acid (H2SO4) was selected as a milder alternative to highly concentrated sulfuric acid which was used in our previous study. This milder solvent requires longer immersion times to partially dissolve PPTA fiber surfaces, therefore a more controllable consolidation process to create all‐aramid composites. After selection of the optimal H3PO4/H2SO4 concentration, PPTA fibers were immersed in the mixed solvent for selected periods of time to partially dissolve PPTA fiber surfaces and convert them into the matrix phase which is needed to fuse the remaining PPTA fiber cores together. Following extraction of the mixed solvent and drying, a consolidated all‐aramid composite was formed. The structure, mechanical‐, and thermal properties of these all‐aramid composites were investigated and reported. Based on high temperature performance of aramid fiber, these all‐aramid composites are promising candidates for high temperature applications. POLYM. COMPOS., 39:3013–3021, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic and elastic properties for type (1) structure of half-Heusler compounds Mn 2 Ge x As 1−x (x = 0.25, 0.50, 0.75, 1.00) have been investigated within GGA and GGA + U methods. Firstly, the Mn 2 Ge 0.5 As 0.5 has a tetragonal structure, while the Mn 2 Ge 0.25 As 0.75 , Mn 2 Ge 0.75 As 0.25 and Mn 2 Ge present a cubic structure. Secondly, the four compounds are all half-metallic (HM) ferrimagnets and their total magnetic moments M t satisfy with the Slater–Pauling rule M t  = 18-Z t . Thirdly, the formation energy and cohesion energy show that they are all thermodynamic stable with GGA method, while with GGA + U method the Mn 2 Ge 0.25 As 0.75 is still thermodynamic stable but the rest three compounds are thermodynamic meta-stable. Finally, with GGA method both Mn 2 Ge 0.25 As 0.75 and Mn 2 Ge 0.5 As 0.5 are mechanical stable under pressure 0–4 GPa, while the Mn 2 Ge 0.75 As 0.25 and Mn 2 Ge lose mechanical stable when the pressure exceed 1.3 and 0.5 GPa, respectively. But with GGA + U method the four compounds are all mechanical stable under pressure 0–4 GPa. [ABSTRACT FROM AUTHOR]

The structural, electronic, elastic, thermodynamic, magnetic, and optical properties of yttrium-based full-Heusler alloys of the form Y 2 CrZ (Z = Si, Ge, Sn) have been studied by first-principles calculations. The stable half-metallic ferrimagnetic characters, which are maintained in the lattice constant ranges 6.365–7.057 Å ( Y 2 CrSi ), 6.496–7.163 Å ( Y 2 CrGe ), and 6.515–7.385 Å ( Y 2 CrSn ), ensure their potential application in spintronics and magnetoelectronics. The total magnetic moment of 2 μ B per formula unit satisfies the Slater-Pauling rule M t = 18 - Z t . The formation energy E f , cohesion energy E c , spin-up band gap E g ↑ , shear modulus G , bulk modulus B , Young’s modulus E , Debye temperature Θ D , melting temperature T melt , static dielectric constant ε 1 ( 0 ) , maximum imaginary part of the dielectric constant ε 2 ( ω ) max , maximum reflective index R ( ω ) max , and static refractive index n ( 0 ) decrease for Y 2 CrSi , Y 2 CrGe , and Y 2 CrSn successively. Increases in both Poisson’s ratio υ and Pugh’s ratio B / G indicate the ductile character increases for Y 2 CrSi , Y 2 CrGe , and Y 2 CrSn successively. The highest global maximum value in the energy loss function L ( ω ) spectra of these three alloys indicates that Y 2 CrSn is the most suitable material to make a far-ultraviolet photodetector. [ABSTRACT FROM AUTHOR]

Employing the spin-polarized first-principles calculations, we have investigated the structural, elastic and electronic properties of marcasite FeS 2 (m-FeS 2 ) under pressure from 0 to 15 GPa. At zero pressure, the m-FeS 2 is a non-magnetic semiconductor with an indirect band gap of 1.17 eV. The conduction band minimum (CBM) is mainly contributed by Fe-t 2g states and a little by Fe-e g states, while the valence band maximum (VBM) is completely contributed by Fe-t 2g states. The m-FeS 2 is mechanically stable in the range of considered pressure. The c axis is the easiest to compress, while b axis is the hardest to compress. Both the brittle nature and covalent combination are observed for m-FeS 2 . With increasing pressure, the bulk modulus, shear modulus, Young's modulus, Poisson's ratio, anisotropy index A U , density, longitudinal, transverse, average elastic wave velocities, Debye temperature and minimum thermal conductivity of m-FeS 2 increase smoothly, and both a small red shift for VBM and a small blue shift for CBM result in an increase of band gap. [ABSTRACT FROM AUTHOR]

The structural, elastic, electronic and optical properties of FeX 2 (X = S, Se, Te) with orthorhombic (space group Pnnm) structure have been investigated through the first-principles calculations. The calculated lattice constants, internal structure parameters and two kinds of Fe-X bond lengths agree reasonably with the experimental results. The corresponding single crystal elastic constants, polycrystalline elastic moduli, transverse, longitudinal, average elastic wave velocities, Debye temperature and minimum thermal conductivity decrease from FeS 2 to FeTe 2 while the elastic anisotropy index increases from FeS 2 to FeTe 2 . All the three compounds show the brittle nature and covalent bonding. The orthorhombic FeX 2 are non-magnetic semiconductors with indirect band gaps of 1.17eV, 0.64eV and 0.27eV, respectively. There have strong hybridizations between Fe-d orbitals and X-p orbitals. The real part and imaginary part of the dielectric function, refractive index and absorption coefficient are obtained and analyzed, the results show that the three compounds possess excellent absorption properties in ultraviolet and visible light regions. Both elastic properties and optical properties exhibit obvious anisotropy in the three compounds. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic and optical properties of the yttrium-based binary Heusler alloy Y 3 Si , ternary Heusler alloy Y 2 CrSi and quaternary Heusler alloy ScYCrSi have been studied by first-principles calculations. The results show that the preferred configurations of Y 3 Si , Y 2 CrSi and ScYCrSi alloys are DO 3 - FM , Hg 2 CuTi − FM and YI − FM configurations, respectively. The Y 3 Si alloy is a conventional metal ferromagnet. While the Y 2 CrSi and ScYCrSi alloys are HM ferromagnets with spin-up band gaps of 0.682 eV and 0.862 eV as well as the HM characters are maintained in the lattice constant ranges of 6.365–7.057 Å and 6.029–7.129 Å, respectively, ensuring potential applications in spintronics. The total magnetic moments of the Y 2 CrSi and ScYCrSi alloys are all 2 μ B /f .u . , satisfying the Slater-Pauling rule M t = 18 - Z t . Among three alloys considered, the Y 2 CrSi alloy has the lowest static dielectric constant, static reflective index, static refractive index, global maximum energy loss function but the highest maximum imaginary part. The phonon dispersion spectra show both Y 2 CrSi and ScYCrSi alloys are dynamically stable, while the Y 3 Si alloy is dynamically unstable. [ABSTRACT FROM AUTHOR]

The investigations of the electronic and magnetic properties show the binary Heusler alloys ZCl 3 (Z = Be, Mg, Ca, Sr) are half-metallic (HM) ferromagnets with an integer magnetic moment ( M t ) of 1 μ B /f.u.. The alloy BeCl 3 is thermodynamic meta-stable, while other alloys are thermodynamic stable according to their cohesive energies and formation energies. Moreover, wide HM regions for alloys ZCl 3 (Z = Be, Mg, Ca, Sr) show their HM characters are robust when the lattices are expanded or compressed under uniform and tetragonal strains. Finally, some optical properties are analyzed in detail, such as the dielectric function, the absorption coefficient, the refractive index and the extinction coefficient. [ABSTRACT FROM AUTHOR]

In this paper, the geometrical, electronic, and magnetic properties of nonmetal (B, C, N, F, Si, P, or S) atom doping of g-ZnO monolayer supercell have been comprehensively calculated using the first-principle method. The structural optimization implies that nonmetal atom doping of g-ZnO monolayer leads to the structural distortion around the doping atoms compared with pure g-ZnO sheet. We find that g-ZnO monolayer with one O atom per supercell substituted by one B or C atom is ferromagnetic half metal, and that substituted by one N, Si, or P atom exhibits a ferromagnetic semiconductor feature, while that substituted by one F or S atom appears to be nonmagnetic semiconductor. The total magnetic moments mainly originates from the spin polarization of the doping atom (B, C, N, Si, and P), and the rest comes from the nearest Zn and O atoms. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of (ZnO) 12 clusters doped with Cr atoms have been investigated by using spin-polarized first-principles calculations. The exohedral a3 isomer is favorable than endohedral a2 isomer. The isomer a1 and a5 respectively have the narrowest and biggest gap between highest unoccupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) of 0.473 and 1.291 eV among these five monodoped isomers. The magnetic moment may be related to the local environment around the Cr atom that the a2 isomer whose total magnetic moment is 6 μ B while the other monodoped isomers which all isomers have nearly total magnetic moments 4 μ B . For Cr-doped (ZnO) 12 on a1 or a3 isomer, the DOS of spin-up channel cross the Fermi level E F showing a finite magnitude near the Fermi level which might be useful for half metallic character. For the bidoped cases, the exohedral isomers are found to be most favorable. Including all bipoed isomers of substitutional, exohedral and endohedral bidoped clusters, the total magnetic moment of the ferromagnetic (antiferromagnetic) state is 8 (0) μ B and the HOMO-LUMO gap of antiferromagnetic state is slightly larger than that of ferromagnetic state. The magnetic coupling between the Cr atoms in bidoped configurations is mainly governed by the competition between direct Cr and Cr atoms antiferromagnetic interaction and the ferromagnetic interaction between two Cr atoms via O atom due to strong p-d hybridization. Most importantly, we show that the exohedral bidoped (ZnO) 12 clusters favor the ferromagnetic state, which may have the future applications in spin-dependent magneto-optical and magneto-electrical devices. [ABSTRACT FROM AUTHOR]

We report the structural, magnetic and electronic properties of the pristine and single TM atoms X (X = Fe, Ru or Os) doped monolayer WS 2 systems based on first-principle calculations. The results show that the W-S bond shows a stronger covalent bond, but the covalency is obviously weakened after the substitution of W atom with single X atoms, especially for Ru (4d 7 5s 1 ) with the easily lost electronic configuration. The smaller total energies of the doped systems reveal that the spin-polarized states are energetically favorable than the non-spin-polarized states, and the smallest total energy of −373.918 eV shows the spin-polarized state of the Os doped monolayer WS 2 system is most stable among three doped systems. In addition, although the pristine monolayer WS 2 system is a nonmagnetic-semiconductor with a direct band gap of 1.813 eV, single TM atoms Fe and Ru doped monolayer WS 2 systems transfer to magnetic-HM with the total moments M tot of 1.993 and 1.962 μ B , while single TM atom Os doped monolayer WS 2 systems changes to magnetic-metal with the total moments M tot of 1.569 μ B . Moreover, the impurity states with a positive spin splitting energies of 0.543, 0.276 and 0.1999 eV near the Fermi level E F are mainly contributed by X - d xy and X - d x 2 - y 2 states hybridized with its nearest-neighbor atom W - d z 2 states for Fe, Ru and Os doped monolayer WS 2 system, respectively. Finally, we hope that the present study on monolayer WS 2 will provide a useful theoretical guideline for exploring low-dimensional spintronic materials in future experiments. [ABSTRACT FROM AUTHOR]

The density functional theory calculations using general gradient approximation (GGA) applying Perdew–Burke–Ernzerhof (PBE) as correlation functional have been systematically performed to research the formation energy, the electronic structures, band structures, total and partial DOS, and optical properties of Nd doping ZnO with the content from 6.25% to 12.5%. The formation energies are negative for both models, which show that two structures are energetically stable. Nd doping ZnO crystal is found to be a direct band gap semiconductor and Fermi level shifts upward into conduction band, which show the properties of n-type semiconductor. Band structures are more compact after Nd doping ZnO, implying that Nd doping induces the strong interaction between different atoms. Nd doping ZnO crystal presents occupied states at near Fermi level, which mainly comes from the Nd 4f orbital. The calculated optical properties imply that Nd doping causes a red-shift of absorption peaks, and enhances the absorption of the visible light. [ABSTRACT FROM AUTHOR]

We have performed a comprehensive calculation about the structures, energy band structures, total and partial density of states of Y doping ZnO with different concentration using the density-functional theory (DFT). The Y doping structures still maintain wurtzite configuration with the increasing of Y content. The research of formation energy shows that Y doping ZnO crystal is energetically stable, and the formation energies reduce with the increasing of Y molar content from 3.125% to 12.5%. The Y doping system exhibits direct band gap like pure ZnO. The Fermi level of doping ZnO crystal shifts upward into conduction, showing the properties of n-type semiconductor and the band gaps of Y doping are larger than that of pure ZnO. There exists a strong localized state at near 5 eV in conduction band, which mainly comes from Y-4d states. The DOS of concentration 12.5% appears a new strong peak at near −24 eV, which mainly originates from the Y-4p states. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic and optical properties of the Zn 1−x Mo x Te (x = 0.00, 0.25, 0.50, 0.75, 1.00) have been investigated by the spin-polarized first-principles calculations. The Zn 0.50 Mo 0.50 Te has tetragonal structure while the Zn 1−x Mo x Te (x = 0.00, 0.25, 0.75, 1.00) crystallize in cubic structures. For Zn 1−x Mo x Te (x = 0.25, 0.50, 0.75, 1.00) alloys, the lattice constant and the volume are found larger than those of pure ZnTe alloy. The Zn 1−x Mo x Te (x = 0.25, 0.50, 0.75, 1.00) is magnetic and the Mo element is found dominant in the bands crossing the Fermi level in the spin-up channel. The Zn 0.75 Mo 0.25 Te and MoTe have half-metallic (HM) behavior. In spin-down channel of the Zn 0.75 Mo 0.25 Te, the Zn atom mainly contributed to the conduction band minimum (CBM), while the valence band maximum (VBM) appears mainly due to contribution of Te element. A positive spin splitting and crystal field splitting of d-states of Mo atom has been observed for Zn 0.75 Mo 0.25 Te alloy. The maximum values of the absorption coefficients α M A X ( ω ) of the Zn 0.50 Mo 0.50 Te alloy along a or b axes are smaller than the absorption coefficient along c axis. The first absorption peak appearing in the energy range of 0.000–1.000 eV for Zn 1−x Mo x Te (x = 0.25, 0.50, 0.75 or 1.00) alloys is the new peak which is not observed in ZnTe. [ABSTRACT FROM AUTHOR]

The structural, magnetic, electronic and optical properties of the pristine and cluster Fe-X 6 (X = S, N, O or F) doped monolayer WS 2 systems have been systematically investigated using the first-principle methods. The results show the cluster Fe-X 6 doped monolayer WS 2 systems under the W-rich condition are more stable than under the S-rich condition, especially for the cluster Fe-O 6 doped monolayer WS 2 system with the most small formation energy of −1.243 eV. The magnetic moment of the isolated Fe atom is 4 μ B , but the calculated magnetic moments of dopant Fe are 1.193, 1.095, −3.019 and −3.269 μ B for the cluster Fe-S 6 , Fe-N 6 , Fe-O 6 and Fe-F 6 doped monolayer WS 2 systems, respectively, which means there are a strong hybrid between dopants Fe and S/N but a weak hybrid between dopants Fe and O/F. Although the pristine monolayer WS 2 system is a nonmagnetic semiconductor, the cluster Fe-S 6 and Fe-F 6 doped monolayer WS 2 systems change to magnetic half-metal with the total magnetic moments of 2.000 and −2.093 μ B , respectively, but the cluster Fe-N 6 and Fe-O 6 doped monolayer WS 2 systems change to magnetic semiconductor with the total magnetic moments of 3.956 and −2.026 μ B , respectively. The smaller the static dielectric constant ε 1 ( 0 ) , the greater the energy gap E g of the corresponding system. The absorption edges of the cluster Fe-N 6 , Fe-O 6 and Fe-F 6 doped monolayer WS 2 systems exhibit the redshift relative to the pristine monolayer WS 2 system, which remarkably increases the absorption of the visible light and so makes them a potentially solar absorbers. [ABSTRACT FROM AUTHOR]

It is currently a prevailing trend to adopt clean energies instead of traditional ones due to the global climate change caused by carbon emissions. Offshore wind farms, in particular, have emerged as a crucial source of renewable energy, owing to their benefits such as no land occupation and abundant resources. However, the design, installation, operation, and maintenance (O&M) of floating wind turbines (FWTs) involve multiple sources of heterogeneous data, which pose challenges to data integration and management, as well as to the simulation and analysis of FWTs. To address this issue, this study proposes a unified framework based on digital twin (DT) to acquire and integrate diverse types of information used throughout the entire life cycle of FWTs. A digital 3D model serves as a medium to enable real-time synchronization and inversion of sensor data, facilitating the simulation and analysis of the global state of FWTs. The proposed framework is evaluated through a case study of a twin-barge float-over project, which includes process simulation, mechanical analysis, and anomaly identification. The results demonstrate that DT can facilitate timely monitoring and analysis of FWTs, and enable visualization of construction plans, early warning of structural abnormalities, and accurate recognition of FWT posture and marine environment. The case study validates the efficacy of the proposed framework in ensuring personnel and equipment safety, optimizing project plans, and improving construction efficiency. • A digital twin-based framework for the whole life cycle of floating wind turbines. • A unified integration method is proposed for multi-source heterogeneous data. • Digital twin is introduced to promotes the simulation and monitoring of structure. • An inversion method for monitoring the global structure status is developed. [ABSTRACT FROM AUTHOR]

The structural, magnetic and electronic properties of the p-type (group VA elements N, P, As or Sb) and n-type (group VIIA elements Cl, Br, I or At) doped monolayer WS 2 systems have been systematically investigated using the spin-polarized first-principle calculations. The results show that whether p-type or n-type doped monolayer WS 2 systems, the greater the atomic radius of the dopant X, the greater the bond length d X − W and height difference h S , but the smaller the bond angle θ W - X - W . All doped systems are easier to form and more stable under W-rich condition than S-rich condition. Specially, the N- and Cl-doped cases are the most stable in p-type and n-type doped monolayer WS 2 systems, respectively. The total magnetic moment M tot of the N-doped system is 0.773 μ B contributed mainly by N-p orbitals, the total magnetic moments M tot of the P-, As- and Sb-doped systems are all approximately zero, and the total magnetic moments M tot of the Cl-, Br-, I- and At-doped systems are 0.543, 0.810, 0.989 and 0.999 μ B , respectively, contributed mainly by the first nearest-neighbor atom W-d orbitals. Although the pristine monolayer WS 2 system is a nonmagnetic semiconductor, the doped system changes to magnetic semiconductor for N-doped system, nonmagnetic metal for P-, As- and Sb-doped systems, magnetic metal for Cl- and Br-doped systems and magnetic half-metal for I- and At-doped systems. [ABSTRACT FROM AUTHOR]

The heavy metal atoms X (X = Au, Hg, Tl or Pb) doped monolayer WS 2 systems have been studied by using the spin-polarized first-principles calculations. Although pure monolayer WS 2 system is a nonmagnetic semiconductor with a direct band gap of 1.820 eV, the Au and Hg atoms doped monolayer WS 2 systems change to half-metal (HM) ferromagnets with the total magnetic moments 0.697 and 1.776 μ B as well as the smaller spin-down gaps 0.605 and 0.527 eV, respectively, while the Tl and Pb atoms doped monolayer WS 2 systems change to magnetic metal with the total magnetic moment 0.584 μ B and a nonmagnetic metal. From the minimization of the formation energy, we find that it is easy to incorporate these heavy metal atoms into monolayer WS 2 system under S-rich condition, especially for the Au doped monolayer WS 2 system not only easily to be formed but also a HM ferromagnet, and thus the best candidate used in the spintronic devices. [ABSTRACT FROM AUTHOR]

The effects of the kinds (M=V, Cr, Mn, Fe, Co, and Ni) and separation distances (d=3.252, 4.600, 5.635, 6.504, 7.273, and 8.607Å for (0, i=1–6) configurations, respectively) of two identical 3d transition metal (TM) atoms M doping on the structural, electronic and magnetic properties of ZnO have been investigated by using spin-polarized first-principles calculations. The formation energies of two identical M atoms doped ZnO systems are lower under O-rich condition than under Zn-rich condition and the formation energy minimization shows the Mn-doped ZnO system is the easiest to form and there exists a clustering trend for two identical M dopants. The ferromagnetic coupling between two identical M atoms under double-exchange mechanism leads to V (0, i=1–6), Cr (0, i=1–6), Fe (0, 2), and Ni (0, i=4–6) cases to be half-metal with integer total magnetic moments of 6, 8, 8, and 4μB, respectively. Whereas, the antiferromagnetic coupling between two identical M atom under superexchange mechanism leads to Mn (0, i=1–6) and Co (0, i=1–6) cases as well as Fe (0, i ≠ 2) and Ni (0, i=1–3) cases to be nonmagnetic semiconductor as well as nonmagnetic metal, respectively. [ABSTRACT FROM AUTHOR]

First-principles calculations have been performed on the structural, electronic and magnetic properties of new yttrium-based full-Heusler alloys Y 2 CrZ (Z = Al, Ga, In) in Hg 2 CuTi structure. For three Y 2 CrZ (Z = Al, Ga, In) alloys, the ferromagnetic states are the most favorable states among the possible magnetic configurations. At equilibrium lattice constants of 7.079, 6.979 and 7.212 Å, the Y 2 CrZ (Z = Al, Ga, In) alloys are half-metallic ferromagnets with spin-up band gaps of 0.622, 0.652 and 0.489 eV, respectively. The formation energies and the cohesion energies indicate the stability of the Y 2 CrZ (Z = Al, Ga, In) alloys. The much higher Curie temperatures T C of 772.947, 842.512 and 966.184 K than room temperature show the Y 2 CrZ (Z = Al, Ga, In) alloys are suitable for spintronics and magnetoelectronics applications. The origins of the spin-up band gaps are attributed to the d-d hybridization (especially) and covalent hybridization. The total magnetic moments of 3 μ B / f .u . for these alloys satisfy the Slater-Pauling rule M t = 18 - Z t . In addition, the HM characters are kept in the lattice constants range from 6.757 to 7.501 Å, 6.716 to 7.422 Å and 6.743 to 7.585 Å for Y 2 CrZ (Z = Al, Ga, In) alloys, respectively. [ABSTRACT FROM AUTHOR]

The structural, electronic and magnetic properties of the quaternary Heusler alloy TiZrCoSn have been investigated firstly by using the first-principles calculations within GGA and GGA+U methods. The structural study shows the Y-type (I) is the most stable configuration among three possible configurations of the TiZrCoSn alloy in FM phase. The GGA calculation shows the TiZrCoSn alloy at its equilibrium lattice constant 6.536 Å is HM ferromagnet with an indirect band gap of 1.043 eV and a HM gap of 0.353 eV in the spin-down channel. The formation energy of −1.041 eV and the cohesion energy of 24.402 eV indicate the stability of the TiZrCoSn alloy. The Curie temperature of the TiZrCoSn alloy is higher than room temperature shows the TiZrCoSn alloy is suitable for spintronic applications. The band gap in the spin-down channel is formed by the bonding ( t 2g ) states and nonbonding ( t u ) states created from the d states hybridisation of transition metal atoms Ti, Zr and Co. The TiZrCoSn alloy has an integer total magnetic moment of 3 μ B / f .u . , satisfying the Slater-Pauling rule μ t = Z t − 18 . In addition, the HM character is kept as hydrostatic strain ranges from −10.3% to 8.4% and tetragonal strain ranges from −16.3% to 20.8%. The similar results are also obtained by GGA+U calculation. [ABSTRACT FROM AUTHOR]

For the new ferrimagnetic Heusler alloys Hf 2 CrZ (Z=Al, Ga, In), the structural, electronic, magnetic, elastic properties have been studied by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA+U). The Curie temperatures T c of the Hf 2 CrZ alloys are estimated with mean field approximation (MFA), and the Curie temperatures T c of these three alloys are higher than room temperature. The Hf 2 CrZ (Z=Al, Ga, In) alloys are found to be half-metallic (nearly half-metallic) ferrimagnets within a certain range of lattice constants, the origin of the gap (pseudogap) is well understood. The total magnetic moments of the Hf 2 CrZ alloys are −1 μ B / f .u . for Z=Al, Ga and In, well consistent with Slater-Pauling rule M t = Z t - 18 . Moreover, their elastic constants and the related mechanical properties have also been calculated and discussed. [ABSTRACT FROM AUTHOR]

For the Ti 2 FeGe Heusler alloy, the surface stability, electronic and magnetic properties of the various (001) surfaces have been studied by using first-principles calculations. The TiGe termination is the most stable one while the GeGe* termination is the most unstable one. Both the density of states (DOS) and atomic magnetic moments (AMMs) of the central layers are similar to the corresponding bulk characters due to no influence of surface effect as we expected. The TiGe termination has the highest spin polarization 96.67%, followed by the TiFe (67.17%), GeGe* (66.51%) and FeFe* terminations (62.02%). The TiTi* terminations has the lowest spin polarization 61.31%. The magnetic moments for atoms on the surfaces and subsurfaces of these terminations are different from the bulk case. [ABSTRACT FROM AUTHOR]

For the Ti 2 FeSn Heusler alloy, the thermodynamic stability, electronic and magnetic properties of the five different terminations FeFe*, TiFe, TiTi*, TiSn and SnSn* of the (100) surface have been studied by using first-principles calculations. The results show that, the TiSn termination is the most stable one while the SnSn* termination is the most unstable one. Both the density of states (DOS) and atomic magnetic moments (AMMs) of the central layers are similar to those of the bulk Ti 2 FeSn case due to no influence of surface effect as we expected. The TiSn and TiFe terminations exhibit half-metallic character with 100% spin-polarizations at the Fermi level and with the spin-down band gaps of 0.36eV and 0.08eV, respectively. The TiSn termination with the lowest surface energy is the most suitable one in the spin-transfer torque magnetic random access memories (STT-MRAM) devices. The spin polarizations of the FeFe*, TiTi* and SnSn* terminations are 74.9%, 72.8% and 72.1%, respectively. [ABSTRACT FROM AUTHOR]

The spin-polarized first-principles calculation is performed to investigate the structural, electronic, magnetic and optical properties of the Zn 1 - x Ni x O systems with x=0.00, 0.25, 0.50, 0.75, 1.00. Except for Zn 0.5 Ni 0.5 O with a tetragonal structure, the other Zn 1 - x Ni x O systems are cubic structure. Although pure ZnO is a nonmagnetic semiconductor with a band gap of 1.43 eV, the Zn 0.75 Ni 0.25 O , Zn 0.5 Ni 0.5 O , Zn 0.25 Ni 0.75 O and NiO systems are completely half metal and thus usable in spintronic devices. The tetrahedral crystal field of the surrounding four O anions splits Ni-3d states into triply degenerate t 2g ( d xy , d yz , d zx ) states with higher energy and doubly degenerate e g ( d z 2 , d x 2 - y 2 ) states with lower energy. The magnetic moments of the Zn 1 - x Ni x O systems are mainly contributed by Ni atom with the small parallel contributions of O and Zn atoms. With increasing Ni concentration, the atomic magnetic moments μ ¯ Ni , μ ¯ O , and μ ¯ Zn , total magnetic moment μ tot , conduction band (CB) and valence band (VB) edge spin splittings Δ E C and Δ E V , spin polarized crystal field splittings Δ E ↑ and Δ E ↓ , spin exchange splitting Δ x ( d ) , static dielectric constant ε 1 ( 0 ) and refractive index n ( 0 ) , new appeared small absorption peak at 0–4 eV increase, while the exchange constants N 0 α and N 0 β , original huge narrow absorption peak around 45 eV decrease. [ABSTRACT FROM AUTHOR]

The spin-polarized first-principles calculations are performed to study the structure, electronic, magnetic and optical properties of the pure, Mn doped and Mn-X (X = F, Cl, Br, I and At) co-doped monolayer WS 2 systems. Although the pure monolayer WS 2 system is a nonmagnetic semiconductor with a direct band gap of 1.820 eV, the Mn doped (Mn-Br co-doped) monolayer WS 2 systems change to half-metal (HM) ferromagnet with a total magnetic moment M tot of 1 μ B (-2 μ B ) and the spin-down band gap E g ↓ of 1.262 eV (spin-up band gap E g ↑ of 1.321 eV) and thus useable in the spintronic devices. The Mn-F, Mn-Cl, Mn-I and Mn-At co-doped monolayer WS 2 systems remain the nonmagnetic semiconducting character with the smaller band gaps E g of 0.667, 0.578, 0.558, and 0.564 eV, respectively. Comparing the formation energies E form , we find that it is the lowest for the Mn-F co-doped monolayer WS 2 system and increases for the Mn-F, Mn-Cl, Mn-Br, Mn-I and Mn-At co-doped cases successively, indicating the Mn-F co-doped monolayer WS 2 system is the most stable. The Mn doped monolayer WS 2 system has the highest static dielectric constants ε 1 ( 0 ) and ε 2 ( 0 ) , refractive indices n ( 0 ) and k ( 0 ) . The absorption coefficients α ( ω ) show the pure monolayer WS 2 system has the highest transmittance in low energy region. Meanwhile, the pure monolayer WS 2 system has larger absorption from 6 to 9.5 eV and thus is more suitable to make a near-ultraviolet (6–9.5 eV) photodetector, while all doped monolayer WS 2 systems are more suitable to make an infrared photodetector due to their red-shift phenomenon. [ABSTRACT FROM AUTHOR]

Based on the pure quasi-P wave equation in transverse isotropic media with a vertical symmetry axis (VTI media), a quasi-P wave equation is obtained in transverse isotropic media with a tilted symmetry axis (TTI media). This is achieved using projection transformation, which rotates the direction vector in the coordinate system of observation toward the direction vector for the coordinate system in which the z-component is parallel to the symmetry axis of the TTI media. The equation has a simple form, is easily calculated, is not influenced by the pseudo-shear wave, and can be calculated reliably when δ is greater than ε. The finite difference method is used to solve the equation. In addition, a perfectly matched layer (PML) absorbing boundary condition is obtained for the equation. Theoretical analysis and numerical simulation results with forward modeling prove that the equation can accurately simulate a quasi-P wave in TTI medium. [ABSTRACT FROM AUTHOR]

The electronic structures and magnetic properties of the new Heusler alloys Hf 2 CoGa and Hf 2 CoIn have been studied by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). Both Hf 2 CoGa and Hf 2 CoIn Heusler alloys have the half-metallic character and completely (100%) spin polarization at the Fermi level ( E F ) and the indirect band gaps of 0.733 eV and 0.654 eV, respectively, in the minority spin channel. The total magnetic moments µ t are all 2 µ B per formula unit, linearly scaled with the total number of valence electrons ( Z t ) by µ t = Z t −18 and the atomic magnetic moments have localized character due to less affected by deformations. The origin of the indirect band gaps for these two new Heusler alloys is well understood. These two new Heusler alloys are the ideal candidates for spintronic devices. [ABSTRACT FROM AUTHOR]