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1.
LaNi5电子与能量结构的全电子计算   总被引:1,自引:0,他引:1  
在全电子水平上,基于广义梯度近似(GGA)密度泛函和全势能线性缀加平面波方法(FLAPW),计算给出了LaNi5的晶体结构、能带结构、电子密度、状态密度(DOS),以及势能结构;并比较分析了自旋极化(Spin-Polarization)对这些性质的影响.全电子计算的晶体结构与实验结果符合得很好;考虑自旋极化后,仅计算出能量约为降低,而对优化结构的影响不明显.  相似文献   

2.
利用原子簇模型和自旋极化离散变分法(DV-Xα),对Fe-Mn合金中ε -马氏体的电子结构和自旋磁矩进行了计算,结果与实验相符;并讨论了原子间距对磁矩 、局域态密度和Fermi能级的影响。  相似文献   

3.
王风  王新强  聂招秀  程志梅  刘高斌 《物理学报》2011,60(4):46301-046301
采用基于密度泛函理论(DFT)框架下的第一性原理平面波赝势(PWP)方法,结合广义梯度近似(GGA),对三元化合物ZnVSe2晶体的电子结构进行了计算,分析了ZnVSe2晶体自旋极化的能带结构、电子态密度、电荷布居、磁矩等.计算结果表明,三元化合物ZnVSe2会产生自旋极化状态,能带结构和态密度显示为半金属特征,表现出显著的铁磁性行为,具有高达近100%的传导电子自旋极化率,其半金属能隙为0.443eV,理论预测其可能是一种具有一定应用潜能 关键词: 2')" href="#">ZnVSe2 平面波赝势方法 半金属铁磁性 第一性原理  相似文献   

4.
利用传统的密度泛函理论在B3LYP/6-31 G(d)水平上优化了铝簇(Aln ,Aln与Aln-,n=2~9)的几何结构,并利用偶合的微扰的密度泛函理论在B3LYP/6-311 G(3df)水平上计算了核自旋-自旋偶合常数.优化结果表明Aln(n=2~9)中的电子是自旋极化的,与早期的质谱实验一致.核自旋-自旋偶合常数的计算结果表明电子的自旋极化与原子核的自旋取向有密切关系.  相似文献   

5.
本文基于密度泛函理论的第一性原理方法, 在广义梯度近似(GGA)下计算了掺杂过渡金属Cr原子后AlN晶体自旋极化的能带结构、分态密度等性质. 结果表明, 半金属能隙随着掺杂浓度的增大而减小. 文中以掺杂浓度为12.5%的Cr-AlN(2×2×1)为例, 分析了其自旋极化的能带结构、分态密度和磁矩等性质, 发现Cr-3d电子对自旋向下子带导带底的能量位置起决定作用. 随着掺杂浓度的增大, Cr原子间相互作用增强, Cr-3d能带向两边展宽, 导致自旋向下子带导带底的能量位置下降, 从而半金属能隙变窄.  相似文献   

6.
利用基于密度泛函理论的第一性原理方法,在广义梯度近似(GGA)下对Ga_(2n)(n=1~4)团簇进行了几何结构优化和结合能计算,并对其电子结构及成键特性进行了分析.结果表明,Ga_2,Ga_4团簇的基态都是自旋极化态,Ga_6团簇的能量局域极小的八面体结构也具有自旋极化;这些团簇的最外层分子轨道的空间分布是对称的,最外层分子轨道之间的能量相差很小,最外层分子轨道的近简并引起了自旋极化;对称性较高的团簇容易形成近简并的最外层分子轨道.  相似文献   

7.
在Brueckner-Hartree-Fock理论框架内,研究了自旋极化核物质的状态方程及其自旋依赖性,计算了相关的物理量如朗道参数G0和G′0,并着重讨论了三体核力的影响.结果表明:在整个自旋极化度范围内,自旋极化核物质的每核子能量随中子和质子自旋极化度的变化相当精确地满足二次方规律,而且在Brueckner-Hartree-Fock理论框架内,自旋非极化核物质的能量总是比相应的自旋极化核物质的能量低,这表明核物质中不会发生由自旋非极化态向自旋极化态的自发相变.当密度较低时,三体核力对核物质状态方程的自旋依赖性的影响不明显;随着密度的增大,三体核力效应增强,而且三体核力使朗道参数G0和G′0增大,从而使核物质对于自旋涨落的稳定性增强  相似文献   

8.
用从头计算第一性原理对Gd-V化合物进行了电子结构与磁性的理论研究.计算的理论基础是密度泛函理论和局域(自旋)密度近似,并应用了相对论性LMTO-ASA计算方法.结果表明Gd-V的非自旋极化能带均为半金属特征.在进行宽能带的自能修正后GdN的非自旋极化能带是半导体行为(Eg≈019eV).自旋极化的LSDA计算结果表明Gd-V均为半金属性的能带结构,即空带与价带有微弱的交叠.在布里渊区的X点和Γ点,分别有n型和p型色散的能带穿过费米面.对于GdN而言,它的上自旋子带为半金属能带,而下自旋子带却 关键词:  相似文献   

9.
在Brueckner–Hartree–Fock理论框架内,研究了自旋极化的中子物质的状态方程及其自旋依赖性,计算了自旋非对称能及相关的物理量如磁化率和朗道参数G0,并着重讨论了三体核力的影响,结果表明:在整个自旋极化度范围内,中子物质的每核子能量随自旋极化度的变化都满足二次方规律,自旋对称能随密度单调增加,这意味着中子物质中不会发生由自旋非极化态向自旋极化态的自发相变,三体核力的主要效应是使中子物质磁化率随密度减小的速度加快,从而使中子物质的磁化相变更加困难.  相似文献   

10.
本文基于密度泛函理论的第一性原理方法, 在广义梯度近似(GGA)下计算了掺杂过渡金属Cr原子后AlN晶体自旋极化的能带结构、分态密度等性质. 结果表明, 半金属能隙随着掺杂浓度的增大而减小. 文中以掺杂浓度为12.5%的Cr-AlN(2×2×1)为例, 分析了其自旋极化的能带结构、分态密度和磁矩等性质, 发现Cr-3d电子对自旋向下子带导带底的能量位置起决定作用. 随着掺杂浓度的增大, Cr原子间相互作用增强, Cr-3d能带向两边展宽, 导致自旋向下子带导带底的能量位置下降, 从而半金属能隙变窄.  相似文献   

11.
Based on the recently proposed Vosko-Wilk-Nusair interpolation formulae for the correlation energy density of the spin-polarized homogeneous electron liquid, a new parametrized form for the correlation potential for the self-consistent local-spin-density calculations of atoms, molecules and solids is proposed. The total energies and first ionization potentials for a few light atoms are calculated. The influence of the improved spin-polarization dependence on the calculated quantities is investigated, too. The calculated ionization potentials are in good agreement with observed values and are better (in average by 0.3 eV) than the values predicted by the hitherto most commonly used correlation potentials within the local spin density approximation.  相似文献   

12.
The electronic structure and optical properties of the hexagonal intermetallic compound Gd5Si3 are investigated. The spin-polarization calculation of the band spectrum is performed in the local spin density approximation, taking account for the strong electron correlations in the 4 f shell of a Gd ion (LSDA + U method). Optical constants of the compound in the wavelength range of 0.22–15 μm are determined by the ellipsometry technique and some spectral characteristics are calculated. The frequency dependence of optical conductivity in the light quantum absorption region is analyzed on the basis of the calculated electron density of states.  相似文献   

13.
We report the results of first-principles calculations on the electronic structure in ferromagnetic and non-magnetic hexagonal MnV (V=As, Sb, Bi). The calculations are based on the local-spin-density approximation (LSDA) of the density-functional theory (DFT) as well as the atomic sphere approximation (ASA) in the linear muffin-tin orbitals (LMTO) method. For the non-spin-polarized case, the calculated bands in these compounds exhibit p-d mixing in the vicnity of Fermi energy and the Mn 3d bands dominate the antibonding parts of p-d hybride. The spin-polarization in ferromagnetic states are mainly due to the splitting of anti-bonding bands from p-d mixing. The calculated spin moments in these compounds agree fairly well with experimental values and refine previous band calculations. In the spin-polarized band structure, the Mn 3d electrons are found to exhibit week dispersions.  相似文献   

14.
We propose an optical method for the investigation of the quantum dot edge channels by utilizing circularly polarized photoluminescence in the integer-quantum-Hall-effect regime. One of the advantages of our method is that the degree of the spin-polarization of the electrons in the inner- and outer-compressible liquids can be probed separately. The observed polarized photoluminescence spectra can be explained by the calculated electron spin-dependent optical transition probabilities based on the local-spin density approximation.  相似文献   

15.
We calculated the formation energy of single vacancy in V-doped ZnO in different conditions (oxygen or zinc rich) by first principles. Effect of an intrinsic vacancy on the electronic density of states and magnetic moment of V-doped ZnO (Zn15VO16) with and without single vacancy was also calculated. Our calculation was performed by the CASTEP program within spin-polarized GGA approximation implemented in materials studio software. The formation energy showed that oxygen vacancy inclined to stay far from vanadium (V) and zinc vacancy preferred to stay at a position near V. The calculated formation energy also showed that a zinc vacancy may automatically occur but an oxygen vacancy may not appear automatically. Vanadium doping introduced spin-polarization around Fermi level. For an energy favorable vacancy, an oxygen vacancy had little effect on the electronic density of states. A zinc vacancy made the spin-polarization peaks around Fermi level broaden and decreased their magnitude. For the magnetic moment in energy favorable configurations, an oxygen vacancy had little effect on the magnetic moment; a zinc vacancy significantly decreased the magnetic moment (as high as 63.7%). Changes in magnetic moments were consistent with electronic density of states. Our calculation may interpret various experimental magnetic moment values. Our work also provided a reference for preparing V-doped ZnO-based dilute magnetic semiconductors.  相似文献   

16.
Applying the classical-map hypernetted-chain method (CHNC) developed recently by Dharma-wardana and Perrot, we have studied the temperature and spin-polarization effects on electron correlation in the uniform quantum two-dimensional gas (2DEG) over a wide range of temperature T and spin-polarization ζ. The quantum fluid at the temperature T is mapped to a classical fluid at the temperature Tcf given by Tcf2=T2+Tq2, where the quantum temperature Tq is determined by comparing the calculated correlation energy to that of Monte Carlo results for the fully spin-polarized quantum system at zero temperature. By the iterative solution of the modified HNC equation and the Ornstein-Zernike equation, we have obtained the pair distribution function (PDF) and correlation energy for the two-component classical 2DEG with a classical fluid temperature Tcf. The anti-parallel bridge function B12(r) appearing in the modified HNC equation is determined by using the Monte Carlo correlation energy at T=0 or STLS (Singwi-Tosi-Land-Sjölander) result at T>0 and the numerical solution to the Percus-Yevick (PY) equation for the system of hard disks. By calculating the Pauli potential, the bridge function, PDFs, structure factors and correlation energy, we have shown that in some cases, the properties of the uniform quantum 2DEG depend remarkably on the temperature and spin-polarization.  相似文献   

17.
Th. Duden  R. Zdyb  M. S. Altman  E. Bauer   《Surface science》2001,480(3):145-152
The magnetic domain structure and the microcrystalline structure of ultrathin Co layers on W(1 1 0), W(1 0 0) and W(1 1 1) surfaces are studied with low energy electron microscopy with and without spin-polarization with the goal to shed some light on the importance of the various parameters which determine the micromagnetic structure.  相似文献   

18.
M. Idrish Miah 《Optics Communications》2012,285(21-22):4427-4430
An investigation of the electronic spin-generation in gallium arsenide is performed using the perturbation theory of the spin transport model in the long wavelength limit, where electron–electron and electron–phonon interactions are ignored. The spin polarizations of the conduction-band-electrons in dependences of the excited one- and two-photon energies are estimated. For both cases, the spin-polarization is found to depolarize for excitation energies equal to or larger than the energy gap of the split-off band to the conduction band. The results, however, show that an enhancement of the spin-polarization is achieved by multiphoton excitation of the bulk semiconductors. The calculated results are compared with those obtained in recent experiments. A good agreement between theory and experiment is obtained.  相似文献   

19.
赵永红  刘邦贵 《中国物理 B》2008,17(9):3417-3421
In order to search for promising candidates for spintronic applications, this paper systematically studies three ternary compounds based on Mn5Ce3 by using a full-potential linearized augmented plane wave method within the density functional theory. Through structure optimization and electronic structure calculations, it finds that Mn4FeCe3 and MnaCoCe3 have much higher spin-polarization than original intermetallic compound Mn5Ce3, although the spin polarization of MnaNiCe3 is lower than that of Mn5Ce3. The calculated result is in agreement with experiment in the case of Mn4FeCe3. Both of them can be taken as promising candidates for spintronics applications because of their high spin-polarization and compatibility with semiconductors.  相似文献   

20.
A relativistic theory of LEED has been applied, in the energy range from 0 to 200 eV, to (111) and (001) faces of Pt and Au. The calculated intensity versus energy profiles are in good agreement with experimental data, which, in particular, provides support for interpreting the observed surfaces as unreconstructed. As a consequence of strong spin-orbit coupling, large spin-polarization peaks are found, partly in conjunction with intensity maxima. As a rough guide to diffraction conditions, at which both polarization and intensity are sizeable, a simple kinematic model might be of some use.  相似文献   

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