Energy Dispersion Curves Research Articles

Exploring the structural, electronic, mechanical, magnetic and optical properties of Cs-based hydride-perovskites CsXH3 (X = Cr, Mn) for hydrogen storage application

Low cast hydride-perovskites are more efficient in power conversion and for energy storage. Here in, structural investigation, electronic, mechanical and optical properties of hydrogen based CsXH3 (X = Cr, Mn) compounds using the density functional theory. The result shows that both materials crystallize into cubic structure. The thermodynamic and dynamic stabilities are conformed through formation energy and phonon dispersion curve. The optimized lattice constants are 3.52 Å and 3.54 Å for CsCrH3 and CsMnH3 respectively. Both materials are found to be half metallic in nature. IR-Elast package are used to obtain elastic constants. The elastic study presents that both materials are ductile and have anisotropic nature. The optical parameters are studied in the range of 0–10 eV. The optical results show that both materials have an excellent optical absorption. The values obtained of gravimetric hydrogen storage capacity for these compounds are 1.55 % and 1.58 % for CsMnH3 and CsCrH3 respectively indicating that these materials can be an excellent candidate for hydrogen energy storage.

First-Principles insights to probe structural and opto-electronic properties of [formula omitted] (Y=Mg, Sr) halide perovskites with variety of DFT methods

This study reports the structural, electronic, optical, phonon, thermodynamic and thermoelectric properties of AgYF3 (X=Mg, Sr) for photovoltaic and energy applications. We performed first principles calculations using full potential linearized augmented plane wave, FP-LAPW method implemented in Wien2k. The generalized gradient approximations of Perdew–Burke–Ernzerhof PBE-GGA, and PBE revised for solids, PBEsol, is employed for structural optimization of these lead free halide perovskites. The Birch–Murnaghan energy volume curve fitting comprehend the structural stability. The optimized lattice constant of AgMgF3 and AgSrF3 obtained with PBE-GGA(PBEsol) is 3.99(3.92)Å and 4.42(4.65)Å. The stability is further tested with the help of formation energy and positive phonon dispersion curves calculations. For the calculations of explicit electronic and optical properties, we also employed Tran–Blaha modified Beck–Johnson (TB-mBJ) and Strongly Constrained but Appropriately Normed, SCAN, exchange and correlations functionals. The electronic band gap of AgMgF3 computed with PBEsol, TB-mBJ and SCAN is 1.96 eV, 5.25 eV and 2.59 eV exhibiting M-Γ indirect band gap. The band gap energy of AgSrF3 is 2.06 eV, 6.42 eV and 2.70 eV with PBEsol, TB-mBJ and SCAN. The indirect band gap nature of AgSrF3 is confirmed by PBEsol and TB-mBJ while it anticipated direct band gap behavior with meta-GGA SCAN. The different optical parameters like dielectric constant, optical conductivity, energy loss function, absorption, reflectivity and refractive index are calculated to assess optical activity of both perovskites. Comprehensive electronic and optical analysis advocates the utility of AgMgF3 and AgSrF3 for different applications is solar technology and optoelectronic devices.

First-principles study of the structure, electronic and optical properties of monolayer ZrX3 (X = S, Se, Te).

The structure, electronic and optical properties of single-layer transition metallic chalcogenides ZrX3 (X = S, Se, Te) have been studied by density functional theory. The electron energy dispersion curve shows that ZrX3 has semiconductor properties, in which the conduction band is mainly contributed by the correlated states of the Zr-d orbital, and the valence band is mainly contributed by the correlated states of the X-p orbital. It is found that b-axis and biaxial strain have great influence on the bandgap and the shift of density of states is also large. At the same time, the peak value of density of states increases greatly when biaxial strain is applied. It is of guiding significance for selecting suitable substrates to prepare two-dimensional ZrX3 materials to study their electronic properties. The calculation of optical constants confirms that ZrX3 has strong optical anisotropy. In the visible range, the light absorption efficiency of ZrX3 in the direction of electric field polarization [100] is higher than that in the direction of [010]. The reflectance spectral results show that ZrS3 and ZrSe3 in the [100] directions have the highest reflectance, and ZrTe3 in the [010] direction has the highest reflectance, even in the long electromagnetic radiation range (up to 10eV), which is of great significance for the construction of visible optical devices. All computations have been carried out based on density functional theory (DFT) as implemented in the CASTEP code. The pseudo-potential is adopted by the norm conserving, and the exchange correlation functional is adopted by the Perdew-Burke-Ernzerhof in local generalized gradient approximation (GGA).

A comprehensive ab-initio study of Cs3Sb2X9 (X= Cl, Br) novel halide perovskites for solar cell applications

Two-dimensional perovskite materials have recently attracted significant interest in solar cell applications. This study employed DFT calculations to investigate the structural, electronic, optical, magnetic, thermal properties and spectroscopic limited maximum efficiency (SLME) of Cs3Sb2X9 (X = Cl, Br) perovskites. The dynamic vibrational stability was calculated using the phonon energy dispersion curve; results show that Cs3Sb2X9 (X = Cl, Br) is dynamically stable. The electronic band structure revealed that these materials exhibit semiconductor behavior with energy bandgaps of 2.41 eV and 1.77 eV for Cs3Sb2Cl9 and Cs3Sb2Br9, respectively. The Cs3Sb2Br9 shows higher absorption and conductivity at comparatively lower frequencies of absorbed light. Furthermore, the magnetic characteristics of the investigated compounds demonstrate that there are no net magnetic moments. The thermodynamic properties analysis indicated a strong correlation between heat capacity and temperature. We have used SLME analysis to determine the theoretical power conversion efficiency for Cs3Sb2X9 (X = Cl, Br) perovskites. The determined results of SLME show that Cs3Sb2Cl9 and Cs3Sb2Br9 exhibit SLME values of 12.63 % and 26.40 %, respectively, at 298.15 K, suggesting that both compounds can be used in solar cells.

Thermoelectric, mechanical, and pressure sustained half-metallic properties of BaInO3 perovskite for spintronics applications: DFT computation

Oxide perovskites continue to promote research interest because of their concurrent use in spintronic and thermoelectric applications. The electronic, magnetic, and thermoelectric properties of new half-metallic BaInO3 perovskite are investigated using the density functional theory. The structural and thermodynamic stability of the proposed perovskite is provided by the tolerance factor, octahedral factor, formation energy, and phonon dispersion curves. The structural relaxation curves reveal that the ground state is ferromagnetic. The generalized gradient approximation and mBJ band structure plots show that the half-metallicity exclusively results from the strong exchange splitting of 2p-bands at the Fermi level. Compared with PBE, mBJ depicts highly localized magnetic moments around oxygen along with enhanced half-metallic gaps and band gaps in the spin-up channel. Under a compressive strain, the system undergoes a magnetic phase transition from half-metallic ferromagnet to non-magnetic metal at 30 GPa. The elastic stability at the studied pressure range has been verified from Blackman’s and Every’s diagrams. The material remains ductile and exhibits moderate elastic anisotropy in the studied pressure range. The quasi-harmonic Debye model is employed to study the temperature and pressure effects of thermodynamic parameters. The computed transport properties including the Seebeck coefficient and spin-Seebeck coefficient predict reasonable thermoelectric performance in generating thermally induced spin-polarized current and spin current, respectively. Such a detailed study of this material could open prospects in spintronic as well as waste energy recovery devices.

First-principles study on hydrogen storage properties of the new hydride perovskite XAlH3 (X=Na, K)

First-principles were employed to research the hydrogen storage capacities and structure, mechanic, electronic, optical, dynamical, thermodynamic properties of XAlH3 (X = Na, K) compounds. The investigation of elastic constants, formation energy and phonon dispersion curve reveals that the XAlH3 compounds possesses mechanical, thermodynamic and dynamic stability. By calculating the B/G, it is evident that NaAlH3 has ductility and KAlH3 has brittleness. Moreover, the chemical bonding of XAlH3 compounds is ionic. According to the results obtained from the electronic property analysis, these compounds are metal nature. Additionally, the internal charge transfer of the two compounds was studied by Bader partial charge analysis. The optical properties show that the NaAlH3 hydride has higher static dielectric function than that of KAlH3. The thermodynamic properties of these hydrides have been studied, including energy, heat capacity, free energy, and the entropy variation with temperature. Furthermore, NaAlH3 and KAlH3 have high hydrogen storage capacities, which are 5.40 wt% and 4.19 wt%, respectively. This study has revealed for the first time the characteristics of XAlH3 hydrides, bringing new potential options for hydrogen storage materials.

Combined effect of rashba spin-orbit interaction, hydrostatic pressure and temperature on energy dispersion based ballistic conductance of InAs tunnel-coupled (double) quantum wire under exterior magnetic and electric field

In this work the change in energy dispersion curve and ballistic conductance for InAs tunnel-coupled double quantum wire (DQWR) under the influence of the external magnetic field, electric field, hydrostatic pressure, temperature, and Rashba spin-orbit interaction (SOI) are studied theoretically in detail. A constant magnetic field transverse to the fundamental plane is applied to the DQWR. The Landuer-Büttiker formalism is used to determine the transport characteristics, and the energy eigenvectors and eigenvalues are derived within the parameters of the diagonalization approach. The numerical results indicate that the energy spectra of the system are influenced by external factors such as magnetic field, electric field, temperature, hydrostatic pressure, and Rashba SOI, resulting in variations in lateral/vertical and downward/upward shifts. These factors also cause oscillatory patterns in ballistic conductance due to the oddity of energy subbands. These results have significant implications for the advancement of double-quantum wire-based devices.

High stability and tunable hydrogen evolution material with defect-enhanced photocatalytic properties:penta-BAs5 monolayer

In this work, on the basis of first principles calculations, we theoretically predict a pentagonal structure material called penta-BAs5 and discuss the photocatalytic properties under its intrinsic and defective modes. Formation energy and phonon dispersion curve all proved its high stability. Penta-BAs5 has a 2.38 eV bandgap and has indirect bandgap semiconductor performance. Surprisingly, by analyzing the band edge distribution, the Gibbs free energy changes (ΔG), and applying strain, it is found that penta-BAs5 can spontaneously proceed the hydrogen evolution reaction (HER) can under neutral and acidic conditions. Interestingly, after applying electric field in the range of 0–0.8 eV/Å, the band edge alignment can keep stable. Intriguingly, the hydrogen evolution capacity of penta-BAs5 was greatly improved when the defects were present. Our study predicted a new two-dimensional pentagonal binary compound, broadened the field of the pentagonal structure families, and identified its application prospects in photocatalysis.

DFT approach into the physical properties of MTe3 (M = Hf, Zr) superconductors: A comprehensive study

In this article, we investigated the structural, electronic, mechanical, optical, and superconducting state properties of the trichalcogenides, MTe3(M = Hf, Zr) compounds using the density functional theory. Electronic energy dispersion curves demonstrate that the title compounds are metallic in nature, with a significant contribution from the Te atom. The technologically important mechanical properties (stiffness constant, elastic moduli, brittle/ductile behavior, Poisson’s ratio, elastic anisotropy, machinability index, and hardness) are thoroughly examined and addressed. The value of Pugh’s ratio indicates the ductility (brittleness) of ZrTe3 (HfTe3). The Vickers hardness value is 0.86 and 0.54 GPa for MTe3 (M = Hf, Zr), respectively, which confirms their softness. The value of lattice thermal conductivity (in W m−1 K−1) for HfTe3 (3.64) and ZrTe3 (2.36) is low due to significant phonon scattering as confirmed by the Grüneisen parameter study. The optical constants were computed, which confirmed the strong optical anisotropy of MTe3 (M = Hf, Zr). For ZrTe3, with the electric field polarization along the [100] direction, the highest reflectivity (51.36%) is obtained compared to HfTe3 (45.21%). This shows promise for application as a radiative heat reflector of these two compounds. The superconducting state properties, such as London penetration depth, coherence length, Ginzburg–Landau parameter, and electron–phonon coupling parameters are estimated and discussed. The value of electron–phonon coupling parameters suggests that both compounds are moderately coupled superconductors.

Ab initio insight into the structural, vibrational, electronic, optical, magnetic, and thermal properties of lead-free perovskite Cs3Sb2Cl9 for solar cell application

In recent years, semiconducting lead (Pb) free perovskite materials have become more attractive materials due to their less toxicity. In this study, we have investigated structural, electronic, optical, magnetic, and thermal properties of Pb-free Cs3Sb2Cl9 perovskite material using density functional theory. We have calculated the Energy-Volume (E-V) curve to evaluate the structural stability. The estimated lattice parameters for the studied material are a = b = 7.818 Å and c = 9.436 Å. Electronic properties suggest that Cs3Sb2Cl9 is a semiconductor material with a suitable energy band gap (Eg = 3.214 eV) for solar cell applications. Optical properties like high absorption, high optical conductivity, and peak reflectivity value in the visible region suggest that Cs3Sb2Cl9 is the most promising material for photovoltaic applications. Furthermore, the dynamic vibrational stability has been investigated as a calculated phonon energy dispersion curve, which shows that Cs3Sb2Cl9 is a dynamically stable compound. The spin-polarized calculations show that the material as a whole and even at the elemental bands level has zero resultant magnetic moments. We have also calculated thermodynamic properties, including enthalpy, free energy, and entropy. Therefore, the calculated results suggest that Cs3Sb2Cl9 is a potential candidate for solar cell applications.

First-principles investigation for the hydrogen storage properties of XTiH3 (X=K, Rb, Cs) perovskite type hydrides

The perovskite-type hydride compounds are potential candidate materials in the field of hydrogen storage. This paper presents a systematical study of XTiH3 (X = K, Rb, Cs) using density functional theory. The analysis of formation energy, elastic properties and phonon dispersion curves indicate that all the studied materials are thermodynamically, mechanically and dynamically stable. By analyzing the B/G ratio, it is determined that these compounds are brittle materials. The electronic properties reveal that the XTiH3 compounds exhibit semi-metallic characteristics. The charge transfer characteristics of these compounds were analyzed using Bader partial charges. Moreover, the thermodynamic characteristics of these compounds were investigated and the dependence of their free energy, entropy and heat capacity on the temperature were analyzed. Finally, the gravimetric hydrogen storage capacities of KTiH3, RbTiH3 and CsTiH3 were calculated to be 3.36, 2.22 and 1.65 wt%, respectively. The hydrogen desorption temperatures of KTiH3, RbTiH3 and CsTiH3 were found to be 209 K, 161 K and 107 K, respectively. To our knowledge, this study represents the very first investigation of XTiH3 compounds and offers valuable references to this hydrogen storage material.

Adsorption of 4D and 5D transition metals on antimonene for optoelectronics and spintronics applications

For spintronic devices, the adsorption of transition metal (TM) atoms may provide two-dimensional (2D) materials with enhanced electrical and magnetic characteristics. Herein, the stability, electronic, and magnetic properties of 4d (Ag, Cd) and 5d (Ir, Pt, Au, Hg) TM adsorbed mono-layer antimonene (Sb) are investigated thoroughly using first-principles calculations. We find out the stability and suitability of the material by using different parameters like relative formation energy, thermal stability, and phonon dispersion curve. The adsorption energies suggest that the most favorable position of adsorption is the hollow (H) site where the ground state energy is lowest. In the case of Ir, and Au adsorbed Sb, the metallic and magnetic behavior is observed due to the change of spin-up and down. Adsorption of Ag also reveals metallic behavior but there is symmetry in high and low spin and shows non-magnetic results. Interestingly, the spin-polarized semiconducting state appears in Cd, Pt, and Hg adsorbed Sb and shows non-magnetic semiconductor behavior. Our study reveals that the TMs adsorbed Sb can be used in potential applications like spintronics, magnetic storage devices, optoelectronics, and Nanoelectronics applications.

Comparative study of optical characteristics of SQW and DQWs InGaAs/GaAsSb/AlAsSb based compressively strained heterostructures

InP-based InGaAs/GaAsSb/AlAsSb type-II single quantum well (SQW) and double quantum wells (DQWs) heterostructures are compared on the basis of matrix elements, energy dispersion curves, optical gain, and transition energy. The effect on optical gain due to applied external strain and the influence of In-mole fraction and Sb-mole fraction on momentum matrix element and transition wavelength have also been compared between SQW and DQWs heterostructures. The simulation results show that the transition wavelength is located in the short wavelength infrared region (SWIR). SWIR imaging has various applications such as solar cell inspection, surveillance, electronic board inspection, identification and sorting, and more. For the proposed design, a total optical gain of 7450 cm−1 and 13,681 cm−1 is obtained at 0.75 eV and 0.77 eV transition energies for the SQW and DQWs heterostructures. For 1.5 nm QW thickness and 3x1012 cm−2 injected carrier density at 300 K, the transition wavelength increases from 1.67 μm to 1.82 μm and 1.60 μm–1.77 μm for SQW and DQWs heterostructure, respectively on increasing the mole fraction value of In from 0.5 to 0.8 and when the mole fraction value of Sb increases from 0.5 to 0.8, the transition wavelength increases from 1.69 μm to 1.87 μm and 1.62 μm–1.79 μm for SQW and DQWs heterostructure, respectively.

Bandgap tuning and thermoelectric characteristics of Sc-based double halide perovskites K2ScAgZ6 (Z = Cl, Br, I) for solar cells applications

Using the full-potential linearized augmented plane wave plus local orbitals method within the frame work of density functional theory, the Sc-based double halide perovskites K2ScAgZ6 (Z = Cl, Br, I) are investigated for determining their physical properties. To investigate the structural and thermodynamic stability of these Sc-based double halide perovskites we calculate tolerance factor, formation energy, and phonon dispersion curve using GGA-PBEsol approximation. The calculated values of lattice parameters using GGA-PBEsol are found to be consistent with the available data. Subsequently, the Tran-Blaha modified Becke-Johnson (mBJ-LDA) potential is used for electronic properties. Implementation of TB-mBJ potential is clearly shows that K2ScAgZ6 have indirect bandgap, which is consistent with the literature. To evaluate these double perovskites and reveal their potential use in optical devices, several optical parameters are computed for an incident photon energy range of 0–8 eV. The BoltzTraP code is also employed to investigate temperature dependent electrical characteristic of these compounds in the temperature range of 200–600 K. Investigated halide double-perovskites have been shown to display excellent physical properties for solar cells and renewable energy device applications.

Phase stability, phonon, electronic, and optical properties of not-yet-synthesized CsScS2, CsYS2, and APmS2 (A= Li, Na, K, Rb, Cs) materials: Insights from first-principles calculations

Transparent conducting materials (TCMs) combine two exclusive properties, electrical conductivity and visible-light transparency; which make them a unique class of materials. They are required in a wide range of applications in modern life ranging from touchscreen-based devices, flat panel displays, light-emitting diodes (LED), and solar cells. Most of the commercially and widely used TCMs are n-type, whereas the development of high-performance p-type TCMs remains an outstanding challenge in the actual time. Herein, using the newly developed SCAN meta-GGA and the hybrid HSE06 functionals, we have explored the structural stability and physical properties of not-yet-synthesized ternary materials CsScS2, CsYS2, and APmS2 (A = Li, Na, K, Rb, Cs) to identify promising p-type TCMs. As result, the calculated formation energy, phase diagram and phonon dispersion curves confirm that these materials are thermodynamically stable and feasible to synthesize experimentally. All these materials, have large optical band gaps (larger than 3.4 eV), small hole effective masses (except for LiPmS2), and have no absorption and weak reflectivity of the visible light. Our work demonstrates that these compounds have suitable properties for p-type TCMs applications.

Application of Computer-Aided Precious Metal Materials in Electrochemistry of Ceramic Jewelry Design

In order to solve the electrochemical application of precious metal materials in ceramic jewelry design, a computer-aided design method of precious metal materials in ceramic jewelry was proposed. First, the potential energy surface analyzed in this paper is composed of the sum of disomy and trisomy, with different proportions of disomy and trisomy. Therefore, in the fitting process, the above two relations can be used to measure the contribution of the two-body term and the three-body term, respectively; secondly, from the viewpoint of lattice dynamics, precious metals are of special significance, because they are simple fcc lattice and large and pure single crystals can be obtained. Therefore, their accurate phonon dispersion curves can be obtained experimentally; finally, the phonon dispersion curves along the highly symmetric vector direction are given, and the calculated results are in good agreement with the experimental data. This shows that the new analytical potential energy surface accurately reproduces the interactions inside these crystals. The new analytical potential energy surfaces of the three noble metals correctly reproduce the macroscopic properties of the system, including elastic modulus, cohesive energy, and phonon dispersion curve, as well as important surface features. For all three systems, the order of the surface energies of the unreconstituted surfaces is (110) > (100) > (111), which is also correct. At the same time, the new potential energy surface gives the correct relaxation behavior of the unreconstituted surface.

Thermal Properties of 2D Dirac Materials MN4 (M = Be and Mg): A First-Principles Study.

Recently, a novel two-dimensional (2D) Dirac material BeN4 monolayer has been fabricated experimentally through high-pressure synthesis. In this work, we investigate the thermal properties of a new class of 2D materials with a chemical formula of MN4 (M = Be and Mg) using first-principles calculations. First, the cohesive energy and phonon dispersion curve confirm the dynamical stability of BeN4 and MgN4 monolayers. Besides, BeN4 and MgN4 monolayers have the anisotropic lattice thermal conductivities of 842.75 (615.97) W m–1 K–1 and 52.66 (21.76) W m–1 K–1 along the armchair (zigzag) direction, respectively. The main contribution of the lattice thermal conductivities of BeN4 and MgN4 monolayers are from the low frequency phonon branches. Moreover, the average phonon heat capacity, phonon group velocity, and phonon lifetime of BeN4 monolayer are 3.54 × 105 J K–1 m–3, 3.61 km s–1, and 13.64 ps, which are larger than those of MgN4 monolayer (3.42 × 105 J K–1 m–3, 3.27 km s–1, and 1.70 ps), indicating the larger lattice thermal conductivities of BeN4 monolayer. Furthermore, the mode weighted accumulative Grüneisen parameters (MWGPs) of BeN4 and MgN4 monolayers are 2.84 and 5.62, which proves that MgN4 monolayer has stronger phonon scattering. This investigation will enhance an understanding of thermal properties of MN4 monolayers and drive the applications of MN4 monolayers in nanoelectronic devices.

A DFT study of perovskite type halides KBeBr3, RbBeBr3, and CsBeBr3 in triclinic phase for advanced optoelectronic devices

The structural, electronic, magnetic, optical, vibrational, thermodynamic and mechanical properties of beryllium based perovskite type halides KBeBr3, RbBeBr3, and CsBeBr3 in triclinic phase have been investigated by utilizing PBE + GGA functional based on density functional theory in CASTEP simulation code. The determined lattice constants for considered perovskite type halides are listed as 5.7125 Å, 5.7202 Å and 5.9533 Å for KBeBr3, RbBeBr3, and CsBeBr3, respectively. The electronic properties have been determined and it is observed that these materials show insulator type character. The observed energy band gaps are in the order of 4.0 eV, 4.2 eV, and 4.7 eV for KBeBr3, RbBeBr3, and CsBeBr3, respectively as calculated by hybrid HSE06 functional. The optical properties like dielectric function, absorption coefficient, conductivity, extinction coefficient etc. also predict that the studied perovskite type halides are the potential candidate for optoelectronic devices. Additionally, the dynamic vibrational stability has been calculated and the determined phonon energy dispersion curves predict that these compounds are dynamically stable. Also, the thermodynamic parameters including enthalpy, free energy and temperature time's entropy have been investigated. Moreover, the mechanical and elastic properties of considered materials are also calculated to check their reliability, stability and easy handling for optoelectronic applications. This first principle investigation of computational properties of the novel materials implement an advance route to the theorists and experimentalists for the new potential applications in the renewable and advanced optoelectronic devices.

Study of an Automatic Picking Method for Multimode Dispersion Curves of Surface Waves Based on an Improved U-Net

Surface wave exploration has been increasingly used in near-surface geophysical investigations. However, the accuracy and efficiency of picking dispersion curves are key to surface wave inversion. Traditional dispersion curve extraction requires manual picking, and the extraction accuracy and efficiency depend on the experience and knowledge of the interpreters. Therefore, developing a fast, high-precision and intelligent dispersion curve extraction method is urgent. This paper improves the structure and output of the U-Net neural network and regards the picking process of dispersion curves as an image classification problem, which quickly and accurately extracts dispersion curves from dispersion energy images. After combining the dispersion energy images of synthetic seismic data with the manually extracted dispersion curve and the theoretical dispersion curve obtained by the Schwab-Knopoff algorithm, the ICM (energy image and dispersion curve extracted manually) training set and the ICS (energy image and dispersion curve calculated by Schwab-Knopoff algorithm) training set are created. The synthetic data tests verify the feasibility of the improved U-Net neural network for automatically picking multimode dispersion curves. The dispersion curve picking results corresponding to two different training sets reveal that the U-Net network model obtained from the ICS training sets exhibits better extraction accuracy. Additionally, we analyze the influence of the sample number of the training set on the dispersion curve picking effect of the improved U-Net and conclude that the improved U-Net network has the advantages of a low training set size requirement and a high dispersion curve extraction accuracy. Finally, the trained network extracts the dispersion curves of two groups of measured surface wave data and obtains plausible extraction results, further proving the proposed method’s effectiveness.

The first-principle study of substitutional impurities’ effect on elastic properties of TlInS2layered crystal

The elastic and vibrational properties of the TIInS2 and TlIn(S0.75Se0.25)2 crystals were first calculated applying DFT/PBE method augmented by dispersion correction (DFT/PBE-D). The elastic constants Cij, bulk modulus B, Young's modulus E, shear modulus G, Poisson's ratio σ, and coefficient B/G were calculated for the studied crystals. The phonon energy dispersion curves and partial densities of the phonon states for the TIInS2 and TlIn(S0.75Se0.25)2 were also calculated. The obtained data are comparable with the experimental results. Anomalies occurring in the phonon energies observed for the TlIn(S0.75Se0.25)2 crystal were explained.