共查询到19条相似文献,搜索用时 93 毫秒
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基于密度泛函理论的第一性原理,采用全势线性缀加平面波方法(FPLAPW)和广义梯度近似(GGA)来处理相关能,计算了Cr掺杂SnO2超晶格的电子态密度、能带结构、介电函数、吸收系数、反射率和折射率.研究表明由于Cr的掺入,超晶格SnO2在费米能级附近形成了新的电子占据态,出现了不连续的杂质能带,这是由Cr-3d态和O-2p,Sn-5s态电子所形成.介电谱在0—5.5 eV之间时出现了三个新的介电峰,在高能区介电谱主峰位置发生蓝移,峰值强度减小.吸收谱、反射谱和折
关键词:
超晶格
第一性原理
态密度
电子结构 相似文献
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基于考虑了Fe-3d电子间的库仑作用U和交换作用J的GGA+U方案,应用第一性原理计算系统研究了LiFePO4的晶格动力学性质.我们计算并分析了玻恩有效电荷张量、布里渊区中心的声子频率和声子色散曲线.玻恩有效电荷张量显示各向异性,佐证了LiFePO4中锂离子沿一维通道[010]方向迁移的机理.布里渊区中心点声子频率的计算值和相应的实验结果符合得比较好.
关键词:
4')" href="#">LiFePO4
晶格动力学
第一性原理计算 相似文献
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采用基于密度泛函理论的平面波赝势方法,在局域密度近似下采用线性响应的密度泛函微扰理论计算了LiNH2的晶格动力学、介电性质和热力学性质,得到了布里渊区高对称方向上的声子色散曲线和相应的声子态密度,分析了 LiNH2的红外和拉曼活性声子频率,同时给出它的介电张量和玻恩有效电荷张量. 研究表明,LiNH2存在小的各向异性,计算所得结果与实验值和其他理论值符合较好.最后,利用得到的声子态密度进一步预测了LiNH2的热力学性质
关键词:
密度泛函理论
晶格动力学
热力学性质
第一性原理计算 相似文献
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以2+价的Ba作为填充原子,在x=1.0—1.6,y=0—0.63的组成范围内,系统地研究了Ba填充分数及Fe含量对p型BayFexCo4-xSb12化合物电性能及热性能的影响,探讨了填充原子的氧化价对电性能的影响规律,优化了p型BayFexCo4-xSb12化合物的组成和热电性能,对于富Co组成的Ba0.27FeCo3Sb12试样,本研究得到了0.9最大无量纲热电性能指数(ZT).
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填充分数
载流子浓度
电导率
赛贝克系数
晶格热导率 相似文献
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在第一性原理框架下,采用赝势平面波方法研究了三种Mg2Si同质异相体的晶胞结构、电子结构和弹性性质随压强的变化关系.研究发现,反萤石结构Mg2Si、反氯铅矿结构Mg2Si和Ni2In型Mg2Si分别在压强为0-7 GPa,7.5-20.2 GPa和21.9-40 GPa范围内能够保持结构稳定.计算获得了不同压强下Mg2Si的弹性常数、体模量、剪切模量、杨氏模量、泊松比和各向异
关键词:
态密度
电子结构
弹性常数
第一性原理 相似文献
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Atomistic simulation of site preference, Curie temperature, and lattice vibration of Nd2Co7 - xFex 下载免费PDF全文
The effects of Fe substitution for Co on the structural stability and the site preference of intermetallics Nd 2 Co 7-x Fe x with a hexagonal Ce 2 Ni 7-type structure are studied by using a series of interatomic pair potentials.In Nd 2 Co 7-x Fe x,Fe atoms are substituted for Co atoms with a strong preference for the 6h sites and the order of site preference is 6h,4e,4f,2a,and 12k.Calculated lattice parameters are found to be consistent with the reported results in the literature.The variation behaviour of the Curie temperature of Nd 2 Co 7-x Fe x is explained qualitatively by the exchange interaction model.The properties related to lattice vibration,such as phonon density of states and Debye temperature,are first evaluated for the Nd 2 Co 7-x Fe x compounds. 相似文献
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The local crystal structures and electronic structures of LiMxFe1-xPO4 (M = Co, Ni, Rh) are studied through first-principles calculations. The lattice constants and unit cell volumes are smaller for the Co and Ni doped materials than for pure LiFePO4, while larger than for the Rh doped material. The local structures around M atoms in the doped materials are studied in details. The total density of states (DOS) and atomic projected DOS (PDOS) are all calculated and analysed in detail. The results give a reasonable prediction to the improvement of electronic conductivity through Fe-site doping in LiFePO4 material. 相似文献
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Ay?e ÖzdemirIgor Dubenko Tapas SamantaNaushad Ali Fatma GüçlüSelçuk Kervan Nazmiye Kervan 《Journal of magnetism and magnetic materials》2012,324(6):1258-1261
The crystal structure and magnetic properties of quaternary rare-earth intermetallic borides R3Co29Si4B10 with R=La, Ce, Pr, Nd, Sm, Gd and Dy have been studied by X-ray powder diffraction and magnetization measurements. All compounds crystallize in a tetragonal crystal structure with the space group P4/nmm. Compounds with R=La, Ce, Pr, Nd and Sm are ferromagnets, while ferrimagnetic behavior is observed for R=Gd and Dy. The Curie temperatures vary between 149 K and 210 K. The Curie temperatures in R3Co29Si4B10 (R=Ce, Pr, Nd, Sm, Gd, Dy) compounds are roughly proportional to the de Gennes factors. 相似文献
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This paper calculates the structural parameters, electronic and optical properties of orthorhombic distorted perovskite-type TbMnO3 by first principles using density functional theory within the generalised gradient approximation. The calculated equilibrium lattice constants are in a reasonable agreement with theoretical and experimental data. The energy band structure, density of states and partial density of states of elements are obtained. Band structures show that TbMnO3 is an indirect band gap between the O 2p states and Mn 3d states, and the band gap is of 0.48 eV agreeing with experimental result. Furthermore, the optical properties, including the dielectric function, absorption coefficient, optical reflectivity, refractive index and energy loss spectrum are calculated and analysed, showing that the TbMnO3 is a promising dielectric material. 相似文献
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This paper investigates the structural stability of intermetallics R3Ni13-xCoxB2(R=Y,Nd and Sm) with Nd 3 Ni 13 B 2-type structure and the site preferences of the transition element Co by using a series of interatomic pair potentials.The space group remains unchanged upon substitution of Co for Ni in R3Ni13-xCoxB2 and the calculated lattice constants are found to agree with reports in literatures.The calculated cohesive energy curves show that Co atoms substitute for Ni with a strong preference for the 3g sites and the order of site preference is 3g,4h and 6i.Moreover,the total and partial phonon densities of states are first evaluated for the R 3 Ni 13 B 2 compounds with the hexagonal Nd 3 Ni 13 B 2-type structure. 相似文献
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We investigate the electronic structure of Ag2HgSnSe4 in a wurtzite-stannite structure with the first principles method. This crystal is a direct band-gap compound. In addition the dielectric function, absorption coefficient, reflectivity, and energy-loss function are studied using the density functional theory in the generalized gradient approximation. We discuss the optical transitions between the valence bands and the conduction bands in the spectrum of the imaginary part of the dielectric function at length. We also find a very high absorption coefficient and a wide absorption band for this material. The prominent structures in the spectra of reflectivity and the energy-loss function are discussed in detail. 相似文献
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A study on strain affecting electronic structures and optical properties of wurtzite Mg0.25 Zn0.75O by first-principles 下载免费PDF全文
We have made a first principles study to investigate density of states, band structure, the dielectric function and absorption spectra of wurtzite Mg 0.25 Zn 0.75 O. The calculation is carried out in a-axis and c-axis strain changing in the range from 0.3 to -0.2 in intervals of 0.1. The results calculated from density of states show that the bottom of conduction band is always dominated by Zn 4s and the top of valence band is always dominated by O 2p in a-axis and c-axis strain. Zn 4s will shift to higher energy range when a-axis strain changes in the range from 0.3 to 0, and then shift to lower energy range when a-axis strain changes in the range from 0 to -0.2. But Zn 4s will always shift to higher energy range when c-axis strain changes in the range from 0.3 to -0.2. The variations of band gap calculated from band structure and absorption spectra are also investigated, which are consistent with the results obtained from density of states. In addition, we analyse and discuss the imaginary part of the dielectric function ε 2 . 相似文献