共查询到20条相似文献，搜索用时 15 毫秒
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FU Zhi-Jian JI Guang-Fu CHEN Xiang-Rong GOU Qing-Quan 《理论物理通讯》2009,51(6):1129-1134
The elastic constants and thermodynamic properties of diamond are investigated by using the CRYSTAL03 program. The lattice parameters, the bulk modulus, the heat capacity, the Grüneisen parameter, and the Debye temperature are obtained. The results are in good agreement with the available experimental and theoretical data. Moreover, the relationship between V/V0 and pressure, the elastic constants underhigh pressure are successfully obtained. Especially, the elastic constants of diamond under high pressure are firstly obtained theoretically. At the same time, the variations of the thermal expansion α with pressure P and temperature T are obtained systematically in the ranges of 0-870 GPa and 0-1600 K. 相似文献
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Fen Luo Zhi‐Cheng Guo Xiu‐Lu Zhang Chang‐Ying Yuan Cheng‐An Liu Ling‐Cang Cai 《physica status solidi b》2015,252(1):212-218
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<正>The elastic and thermodynamic properties of NbN at high pressures and high temperatures are investigated by the plane-wave pseudopotential density functional theory（DFT）.The generalized gradient approximation（GGA） with the Perdew-Burke-Ernzerhof（PBE） method is used to describe the exchange-correlation energy in the present work.The calculated equilibrium lattice constant a0,bulk modulus B0,and the pressure derivative of bulk modulus B0’ of NbN with rocksalt structure are in good agreement with numerous experimental and theoretical data.The elastic properties over a range of pressures from 0 to 80.4 GPa are obtained.Isotropic wave velocities and anisotropic elasticity of NbN are studied in detail.It is indicated that NbN is highly anisotropic in both longitudinal and shear-wave velocities. According to the quasi-harmonic Debye model,in which the phononic effect is considered,the relations of（V-V0）/V0 to the temperature and the pressure,and the relations of the heat capacity CV and the thermal expansion coefficientαto temperature are discussed in a pressure range from 0 to 80.4 GPa and a temperature range from 0 to 2500 K.At low temperature,CV is proportional to T3 and tends to the Dulong-Petit limit at higher temperature.We predict that the thermal expansion coefficientαof NbN is about 4.20×10-6/K at 300 K and 0 GPa. 相似文献
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采用基于密度泛函理论的第一性原理赝势平面波方法, 在广义梯度近似下研究了TaB和TaB2在不同压强下的弹性常数、原子结构、电子结构以及超导性质及其对两者物理性质不同进行了比较. 计算结果表明随着压强的增加, 弹性常数和体弹模量随之增加, 而相对晶格常数a/a0, b/b0, c/c0和相对体积V/V0随压强增加而减小. 在高压下, TaB沿着a轴方向的压缩性要比b轴方向大, 而b轴方向的压缩性要比c轴方向大; TaB2是沿着c轴方向的压缩性要比a轴方向的压缩性大. 电子结构分析表明TaB2的原子态杂化程度比TaB的原子态杂化程度要高, 这与TaB2的体弹模量比TaB的体弹模量高的结果相一致. 依据Bardeen-Cooper-Schrieffer超导理论, TaB和TaB2费米能级处态密度的值随着压强的增加而降低, 说明它们的超导转变温度Tc随着压强的增加而降低. 相似文献
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运用基于密度泛函理论第一性原理方法研究了MnPd从立方顺磁到四方反铁磁的相变以及其弹性性质和热力学性质等．结果表明：MnPd合金顺磁立方B2结构在施加了四方应变后,结构不稳定,会发生结构相变形成四方顺磁结构．四方顺磁相弹性稳定,然而在考虑了磁性后,反铁磁四方相比四方顺磁相能量更低,而且弹性和动力学都稳定,说明反铁磁四方相是MnPd的低温结构．从而得出MnPd合金的相变路径为两步：先发生结构相变从顺磁B2立方结构转变为顺磁四方相,再由磁性诱发相变形成反铁磁四方结构．通过准谐近似得到了摩尔比热容,德拜温度等热力学性质． 相似文献
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Z. Charifi H. Baaziz Y. Saeed Ali Hussain Reshak F. Soltani 《physica status solidi b》2012,249(1):18-28
The B1 (NaCl) and B2 (CsCl) structure of rare‐earth monochalcogenides XY (X = La, Ce, Eu, and Y = S, Se, and Te) were investigated with the full‐potential linearized‐augmented plane wave (FP‐LAPW) scheme in the frame of the generalized gradient approximation (GGA). The optimized lattice parameters, independent elastic constants (C11, C12, and C44) at zero and high pressure, bulk modulus B, and its pressure derivative and the shear modulus G were evaluated. Further, the numerical estimates of a set of elastic parameters [Young's modulus E, Poisson's ratio (ν), Lame's coefficients (µ, λ)] of the polycrystalline XY (X = La, Ce, Eu, and Y = S, Se, and Te) compounds (in the framework of the Voigt–Reuss–Hill approximation) were performed. The pressures at which these compounds undergo structural phase transition from B1 (NaCl) to B2 (CsCl) phases were calculated. For rare‐earth monochalcogenides XY, the Debye temperature is also estimated from the average sound velocity. 相似文献
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This paper studies the equilibrium structure parameters and the dependences of the elastic properties on pressure for rutile TiO2 by using the Cambridge Serial Total Energy Package （CASTEP） program in the frame of density functional theory. The obtained equilibrium structure parameters, bulk modulus B0 and its pressure derivative B′0 are in good agreement with experiments and the theoretical results. The six independent elastic constants of rutile TiO2 under pressure are theoretically investigated for the first time. It is found that, as pressure increases, the elastic constants C11, C33, C66, C12 and C13 increase, The variation of elastic constant C44 is not obvious and the anisotropy will weaken. 相似文献
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WANG Yong-Liang CUI Hong-Ling YU Bai-Ru CHEN Xiang-Rong 《理论物理通讯》2008,49(2):489-492
The elastic properties of the wurtzite-type aluminum nitride （w-AlN） are investigated by ab initio plane-wave pseudopotential density functional theory method. The pressure dependences of the normalized primitive cell volume V/Vo, the elastic constants cij, the aggregate elastic modulus （B, G, E）, the Poisson＇s ratio （v）, and the Debye temperature θD are successfully obtained. From the elastic constants of the w-AlN under pressure, we find that the w-AlN should be unstable at higher pressure than 61.33 GPa. 相似文献
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In this paper the elastic and thermodynamic properties of the cubiczinc-blende structure BeS at different pressures and temperaturesare investigated by using textit{ab initio} plane-wavepseudopotential density functional theory method within thegeneralized gradient approximation (GGA). The calculated results arein excellent agreement with the available experimental data andother theoretical results. It is found that the zinc-blendestructure BeS should be unstable above 60GPa. The thermodynamicproperties of the zinc-blende structure BeS are predicted by usingthe quasi-harmonic Debye model. The pressure-volume-temperature($P-V-T$) relationship, the variations of the thermal expansioncoefficient $alpha$ and the heat capacity $C_{V}$ with pressure $P$and temperature $T$, as well as the Gr\"{u}neisenparameter-pressure-temperature ($gamma -P-T$) relationship areobtained systematically in the ranges of 0--90GPa and 0--2000K. 相似文献
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Sabrina Akther Shupra;Most Sumaiya;Md Al-Helal;Md Nurul Huda Liton;Md Kamruzzaman;Abu Kalam Mohammad Farid Ul Islam; 《physica status solidi b》2024,261(3):2300452
A thorough analysis of the structural, elastic, electronic, and optical properties of ScCuO3 perovskite is conducted using density functional theory. The compound's structural and mechanical stabilities are established under pressure. The values of Pugh's ratio (B/G) and the Zener anisotropy factor indicate that ScCuO3 displays ductile behavior and elastic anisotropy under varying pressures. The metallic behavior of ScCuO3 is confirmed by its electronic band structure, which shows that a few valence bands intersect the Fermi level. The Cu-3d and O-2p orbitals overlap near the Fermi level, which is found from the density of states diagram. It is also proclaimed that the Cu-3d states strongly hybridized with O-2p states are observed under applied pressure. Various optical properties (dielectric function, photoconductivity, absorption coefficient, loss function, reflectivity, and refractive index) are also analyzed. The compound has the highest reflectivity and is found in the low-energy region, making it suitable as a coating material for reducing solar heating. The absorption spectra and optical conductivity indicate the metallic nature of ScCuO3, which is supported by the calculations of the electronic band structure. The current study explores the potential applications of ScCuO3 in various optoelectronic devices. 相似文献
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Fen Luo Zhi-Cheng Guo Xiu-Lu Zhang Chang-Ying Yuan Cheng-An Liu Ling-Cang Cai 《Molecular physics》2013,111(12):1501-1507
The study aims at the elastic, mechanical, electronic properties and hardness of Nb2AsC using first principles based on the density functional theory method within the generalised gradient approximation. The calculated lattice parameters of Nb2AsC are in good agreement with the experimental data. The five independent elastic constants are firstly calculated as a function of pressure, and our results indicate that it is mechanically stable in the applied pressure. The elastic anisotropy is examined through the computation of the direction dependence of Young's modulus. The pressure dependences of the bulk modulus, shear modulus, average velocity of acoustic waves and Debye temperature of Nb2AsC are systematically investigated. The band structure and density of states are discussed, and the results show that the strong hybridisations C p–Nb d and As p–Nb d would be beneficial to the structure stability of Nb2AsC. Based on the Mulliken population analysis, the hardness of Nb2AsC is predicted. 相似文献
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TAN Jia-Jin CHENG Yan ZHU Wen-Jun GOU Qing-Quan 《理论物理通讯》2008,50(7):220-226
The lattice parameters, bulk modulus, phase transition pressure, and temperature dependencies of the elastic constants cij of CdSe are investigated by using the Cambridge Serial Total Energy Package （CASTEP） program in the frame of Density Functional Theory （DFT）. It is found that the phase transitions from the ZB structure to the RS structure and from WZ structure to RS structure are 2.2 GPa and 2.8 GPa, respectively. Our results agree well with the available experimental data and other theoretical results. The aggregate elastic modulus （B, G, E, A ）, the Poisson＇s ratio （v）, the Griuneisen parameter （γ）, the Debye temperature θD on pressure and temperature are also successfully obtained. 相似文献
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Muhammad Raza ur rehman Hashmi Muhammad Zafar M Shakil Atif Sattar Shabbir Ahmed S A Ahmad 《中国物理 B》2016,25(11):117401-117401
First-principles calculations by means of the full-potential linearized augmented plane wave method using the generalized gradient approximation with correlation effect correction(GGA+U) within the framework of spin polarized density functional theory(DFT+U) are used to study the structural,electronic,and magnetic properties of cubic perovskite compounds RbXF_3(X = Mn,V,Co,and Fe).It is found that the calculated structural parameters,i.e.,lattice constant,bulk modulus,and its pressure derivative are in good agreement with the previous results.Our results reveal that the strong spin polarization of the 3d states of the X atoms is the origin of ferromagnetism in RbXF_3.Cohesive energies and the magnetic moments of RbXF_3 have also been calculated.The calculated electronic properties show the half-metallic nature of RbCoF_3 and RbFeF_3,making these materials suitable for spintronic applications. 相似文献
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Structural, elastic, electronic and optical properties of hexagonal β‐Nb2N and β‐Ta2N compounds are studied for different pressures. The computational technique is based on a plane wave pseudo potential (PWPP) method. The exchange correlation is treated using a generalized gradient approximation (GGA). We evaluate ground state quantities such as lattice parameter, bulk modulus and its pressure derivative, as well as elastic constants. The calculated equilibrium lattice is in rather good agreement with experimental data. Elastic constants and their pressure dependence are calculated using a static finite strain technique. We derive bulk and shear moduli, Young's modulus and Poisson's ratio for ideal polycrystalline β‐Nb2N and β‐Ta2N aggregates. Also, we present results of densities of states. Furthermore, starting from dynamical optical properties, the static dielectric constant ε(ω = 0) is calculated for both compounds, along with the corresponding static refractive index n(0). The present results are a pioneer quantitative theoretical prediction of elastic, electronic and optical properties in the case of β‐Nb2N and β‐Ta2N compounds. 相似文献
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Yusuf Zuntu Abdullahi Tiem Leong Yoon Mohd Mahadi Halim Md. Roslan Hashim Thong Leng Lim 《哲学杂志》2013,93(24):2077-2088
AbstractMechanical and electronic properties of s-triazine sheet are studied using first-principles calculations based on density functional theory. The in-plane stiffness and bulk modulus for s-triazine sheet are found to be less than that of heptazine. The reduction can be related to the nature of the covalent bonds connecting the adjacent sheets and the number of atoms per unit cell. The Poisson’s ratio of s-triazine sheet is half the value to that of graphene. Additionally, the calculated values of the two critical strains (elastic and yielding points) of s-triazine sheet are in the same order of magnitude to that for heptazine which was calculated using MD simulations in the literature. It is also demonstrated that s-triazine sheet can withstand larger tension in the plastic region. These results established a stable mechanical property for s-triazine sheet. We found a linear relationship of bandgap as a function of bi-axial tensile strain within the harmonic elastic region. The reduced steric repulsion of the lone pairs (px-, py-) causes the pz-like orbital to shift to high energy, and consequently an increase in the bandgap. We find no electronic properties modulation of the s-triazine sheet under electric field up to a peak value of 10 V/nm. Such noble properties may be useful in future nanomaterial applications. 相似文献
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