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The electronic structure, magnetic states, and chemical bonding of a nickel impurity in cubic silicon carbide (-SiC) were studied by the ab initioself-consistent discrete variation method depending on the position of the impurity in the crystal. The interstitial (Ni(i)) and substitution (Ni(s)) positions were considered and more complex (paired) Ni(i)–Si vacancy and Ni(s)–Si(i) types of defects were simulated. 相似文献
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M. V. Ryzhkov T. A. Denisova V. G. Zubkov L. G. Maksimova 《Journal of Structural Chemistry》2000,41(6):927-933
This paper presents a cluster–DV study of the electronic structure of a large fragment of the crystal lattice of a new compound Pb2Fe(CN)6 having a trigonal structure. The electronic energy spectrum and electron density distribution between Fe–C, C–N, and Pb–N are discussed. 相似文献
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三茚基钐(Sm(C9H7)3)的电子结构和化学键 总被引:1,自引:0,他引:1
采用INDO方法研究了三茚基钐的电子结构和化学键。结果表明,钐原子的6s、6p和5d轨道与配位体轨道有不同程度的混合;HOMO和LUMO是由钐原子的5d轨道和配位体原子轨道构成的π型分子轨道;4f轨道是高度定域的,参与成键不超过2%。三茚基钐的化学键具有相当程度的共价性,茚基中碳原子上的净电荷分布不均匀。讨论了三茚基钐的四氢呋喃加合物中的Sm-C键。 相似文献
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利用第一性原理方法研究了掺杂元素Ti, Ni对NaAlH4放氢性能的影响. 计算表明: Ti在NaAlH4中倾向于替代Al原子, 而Ni则倾向于占据间隙位置. 电子结构分析显示Ti替代NaAlH4中的Al位置时与近邻的Al原子产生强烈的相互作用, 破坏[AlH4]基团的结构, 从而改善NaAlH4的放氢性能. Ti替代Na或占据间隙位置时Ti与H原子间存在较强的相互作用, 有可能诱发TiH2相而改善NaAlH4的放氢性能. 与Ti相比Ni对NaAlH4放氢性能的影响较小, 仅当Ni占据间隙位置时才可能对[AlH4]基团产生一定影响. 总体而言, Ti对NaAlH4放氢性能的影响强于Ni的作用, 这与实验观测相吻合. 相似文献
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Bond distances, vibrational frequencies, dissociation energies, electron affinities, ionization potentials and dipole moments
of the title molecules in neutral and charged ions were studied by use of density functional method. Ground states for each
molecule were assigned. The calculated bond distance decreases with the increasing of atomic number of 4d metals, reaches
minimum at RhS, then increases. For cationic molecules, the calculated bond distance decreases to the minimum at MoS+, then increases. The calculated vibrational frequency decreases from YS(YS+) to PdS(PdS+) for both neutral and cationic molecules. The bond ionic character decreases from YS(YS+) to PdS(PdS+) for neutral and cationic molecules. The bonding patterns are discussed and compared with the available studies.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Sc2Ni2In was prepared by a reaction of the elemental components in an are furnace and subsequent annealing at 1070 K. Sc2Ni2In is a Pauli paramagnet and a poor metallic conductor with a specific resistivity of 224 mΩcm at room temperature. Its crystal structure was refined from X-ray powder data: P4/mbm, a = 716.79(1) pm, c = 333.154(8) pm, Z = 2, Rwp = 0.040, and RB(I) = 0.026. Sc2Ni2In crystallizes with a ternary ordered version of the U3Si2-type structure. The nickel and indium atoms occupy [NiSc6] trigonal prisms and [InSc8] square prisms, respectively. These structural fragments are derived from the AlB2 and CsCl-type structures. Semi-empirical band structure calculations reveal Sc2Ni2In to be a nickelide, and the strongest bonding interactions are found for the Sc? Ni contacts, followed by Sc? In and Ni? In. A rigidband model suggests the existence of the isotypic phase Sc2Ni2Sb. 相似文献
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本文对锕系化合物的结构和性质的理论研究进行了规律性总结,并结合我们的研究成果,重点介绍了锕酰冠醚配合物的配位化学、电子结构和化学成键的基本特征。尽管近年来出现越来越多的光谱实验和晶体学数据报道,但是对锕系配合物的电子结构和化学成键的理论研究还不够系统。本文对锕酰冠醚配合物的配位结构、稳定能和光谱性质的计算结果进行了综述。大环配体(硫代)冠醚的腔体大小决定了配合物的结构特征。通过理论研究,在锕酰冠醚配合物中存在具有典型的An≡Oactinyl共价键和An-Oligand和An-Sligand离子键。对于离子键An-Oligand和An-Sligand,An和供电子配体之间通过价原子轨道的径向分布重叠形成微弱的共价相互作用。从U到Cm,配体向金属的电荷转移(LMCT)逐渐显著,导致Am和Cm的氧化态降低,金属离子与配体的作用变弱。这一成键规律和金属氧化态的变化规律,为实验上筛选合理且高效的镧锕分离配体提供重要理论指导。 相似文献
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The electronic energy structure and FeK XANES in monoferrites MgFe2O4, MnFe2O4, NiFe2O4, and ZnFe2O4 were calculated with the FEFF8 program. In both normal (MnFe2O4, ZnFe2O4) and invert (MgFe2O4, NiFe2O4) spinels, hybridization of the p-states of oxygen with the 3d-states of transition metal ions leads to a similarity in the formation of the top of the valence band. In contrast to the magnetic nickel and manganese ions, the nonmagnetic zinc and magnesium ions are not actively involved in chemical bonding. It is shown that when Mn and Fe lie in the same coordination spheres of the absorbing iron atom the 3d-states are split and the curve of the densities of the p-states of transition element ions with different spin orientations changes in shape. 相似文献
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
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用INDO法从正则分子轨道和定域分子轨道讨论了[CuCl_3]~-的电子结构和化学键,铜的4p轨道对成键贡献最大,3d轨道不参与成键。根据[CuCl_3]~-的HOMO和LUMO的原子轨道成份,讨论了它的配位化学性质。 相似文献
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通过第一性原理计算,优化了铁磁性过渡离子掺杂的纤锌矿相硫化锌Fm0.125Zn0.875S(Fm=Fe、Co、Ni)的几何结构,计算了其电子结构,分析了其半金属性及其微观机制。结果表明:对不同的铁磁性杂质离子,Fm0.125Zn0.875S在费米面处的自旋极化率均为-100%,具有半金属性,是潜在的优质自旋注入材料。Fm0.125Zn0.875S具有较宽的自旋带隙,从而具有较高的居里温度和广泛的应用前景。Fe0.125Zn0.875S、Co0.125Zn0.875S和Ni0.125Zn0.875S的2×2×1超胞的磁矩分别为3.96μB、2.90μB和2.00μB,主要来自于铁磁性过渡离子Fe、Co和Ni离子。这3种离子的电子结构分别为eg2↑eg1↓t2g3↑,eg2↑eg2↓t2g3↑和eg2↑eg2↓t2g3↑t2g1↓。 相似文献
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Fu‐Sheng Guo Yan‐Cong Chen Ming‐Liang Tong Akseli Mansikkamki Richard A. Layfield 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10269-10273
Abstraction of iodide from [(η5‐C5iPr5)2UI] ( 1 ) produced the cationic uranium(III) metallocene [(η5‐C5iPr5)2U]+ ( 2 ) as a salt of [B(C6F5)4]?. The structure of 2 consists of unsymmetrically bonded cyclopentadienyl ligands and a bending angle of 167.82° at uranium. Analysis of the bonding in 2 showed that the uranium 5f orbitals are strongly split and mixed with the ligand orbitals, thus leading to non‐negligible covalent contributions to the bonding. Investigation of the dynamic magnetic properties of 2 revealed that the 5f covalency leads to partially quenched anisotropy and fast magnetic relaxation in zero applied magnetic field. Application of a magnetic field leads to dominant relaxation by a Raman process. 相似文献
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Fu‐Sheng Guo Yan‐Cong Chen Ming‐Liang Tong Akseli Mansikkamki Richard A. Layfield 《Angewandte Chemie (International ed. in English)》2019,58(30):10163-10167
Abstraction of iodide from [(η5‐C5iPr5)2UI] ( 1 ) produced the cationic uranium(III) metallocene [(η5‐C5iPr5)2U]+ ( 2 ) as a salt of [B(C6F5)4]?. The structure of 2 consists of unsymmetrically bonded cyclopentadienyl ligands and a bending angle of 167.82° at uranium. Analysis of the bonding in 2 showed that the uranium 5f orbitals are strongly split and mixed with the ligand orbitals, thus leading to non‐negligible covalent contributions to the bonding. Investigation of the dynamic magnetic properties of 2 revealed that the 5f covalency leads to partially quenched anisotropy and fast magnetic relaxation in zero applied magnetic field. Application of a magnetic field leads to dominant relaxation by a Raman process. 相似文献