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91.
A search for configuration space with well-defined topological (Berry) phases corresponding to Jahn-Teller (JT) conical intersection (CI) and Renner-Teller (RT) parabolic intersection (PI) in the linear tetra-atomic molecular system on introduction of bending demonstrates the interesting aspect that these potential intersections may appear in the molecular plane as well as out of the molecular plane. While understanding this aspect is important for following the class of phenomena led by potential intersections, till date, studies on molecular systems, including pairs such as (C2H2+, HCNH) and (N2H2+, HBNH+), have not been able to clarify the issue. The present article includes calculation of nonadiabatic coupling terms involving four low-lying states of slightly bent HCNO+, a motivated choice of tetra-atomic with all four different atoms, to study this aspect associated with JT-CI and RT-PI in a slightly bent linear system. The plane of appearance of these effects has been advocated to be related to the electronic configuration of the concerned states of the molecular system. 相似文献
92.
通过固相燃烧法快速合成了包含{111}、{100}和{110}晶面的单晶去顶角八面体形貌LiZn0.08Al0.01Mn1.91O4正极材料。结果表明,Zn-Al共掺促进了尖晶石型LiMn2O4材料的晶体发育和晶面择优生长,形成了单晶去顶角八面体形貌晶粒,有效抑制了Jahn-Teller效应,减缓了Mn溶解,增强了其晶体结构稳定性,显著提升了合成材料的电化学性能。LiZn0.08Al0.01Mn1.91O4在5C和10C下的首次放电比容量分别为92.6和76.5 mAh·g-1,经过2 000次循环后的容量保持率分别为70.4%和74.8%。即使在15C高倍率下,仍有64.2 mAh·g-1的首次放电比容量,循环800次后容量保持率达到82.2%。与LiZn0.08Mn1.92O4相比,LiZn0.08Al0.01Mn1.91O4正极材料具有较大的Li+扩散系数(1.02×10-11 cm2·s-1)和较小的表观活化能(25.60 kJ·mol-1),表明Zn-Al共掺和单晶形貌调控策略能够降低Li+在脱/嵌过程的能垒和增大Li+在电极材料中的扩散速率。 相似文献
93.
The geometries of one-electron reduced/oxidized species ([TOP]-/[VOP] +) of vanadyl por- phyrin (VOP) have been calculated with PBE1PBE method. The results show that for both [VOP]- and [VOP]+ the ground states are triplet, in which one of the two unpaired electron occupies the dxy orbital of the V atom while the other occupies the n-orbital of porphyrin ring. Thus both [VOP]- and [VOP]+ can be considered as n-radicals. The ground state of neutral VOP molecule is doublet with the unpaired electron occupying dxy orbital of V atom. In contract to the C4v symmetry of neutral VOP molecule, [VOP]- anion has a "rectangular" distorted C2v structure due to Jahn-Teller effect. The linear vibronic coupling constants for the Jahn-Teller active modes of [TOP]- were evaluated and the node patterns of frontier KS orbitals are used to explain the reason why the distortion occurs along specific modes. The ground state [VOP]+ has a porphyrin ring with pronounced bond length alternation due to pseudo-Jahn-Teller effect, causing its symmetry declined from C4v to Ca. The bond length alternation is well explained with the node patterns of re-constructed frontier KS orbitals. 相似文献
94.
First-principle GGA+U calculations were performed on the undistorted rhombohedral R3?m model, the collinear Jahn-Teller distorted monoclinic C2/m model, and six non-collinear Jahn-Teller distortion ordering models of LiNiO2. The zigzag and C2/m models are found to be the most stable and the next most stable structural models, respectively. An energy gap appears for the C2/m and zigzag structures, whereas no energy gap appears for the R3?m structure. Topological analyses were performed on the R3?m, C2/m and zigzag models using the atoms-in-molecules theory and the electron localization function. The results show that the Ni-O interaction is the transit closed-shell interaction, in which the net electron transfer occurs from the Ni ion to the ligand O ions. The Ni-O bond possesses the σ dative bond character and is polarized toward the O ions. In the distorted structures, the bonding electrons around the oxygen atom are strongly polarized toward the long Ni-O bond. 相似文献
95.
Nikolay Smolentsev Grigory Smolentsev Shiqiang WeiAlexander V. Soldatov 《Physica B: Condensed Matter》2011,406(14):2843-2846
GaN:Mn dilute magnetic semiconductors with zinc-blende type of lattice and room temperature ferromagnetism were investigated by the X-ray absorption near edge structure (XANES) with a high accuracy approach of the multidimensional interpolation, which makes it possible to determine the nanoscale local atomic structure around Mn impurities. It is found that Mn atoms are substantially incorporated into the GaN lattice and Jahn-Teller distortion around Mn atom is observed. Our results show that symmetry changes around Mn atom influence on XANES spectrum significantly. Furthermore, the possible impact of local distortions on the magnetic properties is discussed. 相似文献
96.
冯胜奇 《原子与分子物理学报》2011,28(4):591-597
依据Jahn-Teller效应理论与量子理论,利用群论和对称性分析的方法探讨了具有Td对称性构型的C42+分子的T e 系统的Jahn-Teller效应与各向异性问题。构建了T e系统的电声耦合哈密顿量,借助么正平移变换求出了系统的基态与激发态及其能量。结果发现,由于电声耦合作用的缘故,系统发生了Jahn-Teller畸变,畸变导致在系统的势能面上形成了3个具有D2d对称性的势阱。无论系统处在哪一个势阱中,系统原初三重简并的能级都将分裂为两条能级。畸变还导致C42+分子从Td对称性降低到D2d对称性,同时C42+分子的振动频率发生分解,而频率的分解致使C42+分子的各向同性遭到破坏而呈现出各向异性。 相似文献
97.
98.
在统一配体场耦合图像的基础上,构造了d4电子组态过渡金属离子在强场图像下包括所有自旋状态的210×210维完全能量矩阵.通过对角化完全能量矩阵,研究了Cr2+掺杂ZnS的局域晶格结构和Jahn-Teller能.理论计算结果与实验值符合非常好.同时,还研究了Cr2+掺杂ZnS后体系自旋单态对零场分裂参量的贡献.结果表明:自旋单态对二阶零场分裂参量D的贡献可以忽略,但是对于四阶零场分裂参量a和F的贡献却
关键词:
2+')" href="#">ZnS:Cr2+
统一配体场耦合
自旋单态
Jahn-Teller能 相似文献
99.
100.
A new dimorphic copper selenite bromide, Cu5(SeO3)4Br2 was obtained via chemical transport reactions. α-Cu5(SeO3)4Br2, monoclinic (1m) and β-Cu5(SeO3)4Br2, triclinic (1a) polymorphs were produced simultaneously upon reaction of amorphous, partially dehydrated copper selenite and copper bromide. 1m is similar to Cu5(SeO3)4Cl2, whereas 1a is distantly related to Ni5(SeO3)4Br2 and Co5(SeO3)4Br2. Attempts to reproduce synthesis of 1a via exchange reaction between Na2SeO3 and CuBr2 resulted in a new Na2[Cu7O2](SeO3)4Br4 (2). Current study demonstrates for the first time, that both chemical vapor and exchange reactions can be employed in preparation of new selenite halides. 相似文献