Rashba billiards

We study the energy levels of non-interacting electrons confined to move in two-dimensional billiard regions and having a spin-dependent dynamics due to a finite Rashba spin splitting. The free space Green's function for such Rashba billiards is constructed analytically and used to find the area and perimeter contributions to the density of states, as well as the corresponding smooth counting function. We show that, in contrast to systems with spin-rotational invariance, Rashba billiards always possess a negative energy spectrum. A semi-classical analysis is presented to interpret the singular behavior of the density of states at certain negative energies for circular Rashba billiards. Our detailed analysis of the spin structure of circular Rashba billiards reveals a finite out-of-plane spin projection for electron eigenstates.     

Intersections of energy surfaces in quantized Sinai billiards

Degeneracies in the spectra of quantized Sinai billiards are numerically investigated. Two effects recently predicted are observed, namely, (i) a geometric phase of nπ during a circuit surrounding n conical intersections and (ii) neighboring glancing and conical intersections. Experiments in isomorphic flat microwave resonators exhibit excellent agreement with computed eigenvalues and eigenfunctions.     

Mössbauer study of spinel system ZnMn1−x Cr x FeO4

Mössbauer effect of the system of spinels ZnMn_1?x Cr _x FeO₄ is studied forx having values 0, 0·2, 0·4, 0·5, 0·6, 0·8 and 1·0. These compounds show quadrupole splitting which increases with increasing Mn³⁺ ion concentration. It abruptly increases at Mn³⁺ ion concentration at which crystal structure also changes.     

CH3S(X2E)中电子-振动-自旋耦合能级的理论计算

基于透热模型,我们独立开发一套完整的程序包,结合采用量子化学从头计算法研究了CH3S(X2E)自由基中电子-振动-自旋轨道相互作用。透热势能面通过CASPT2/cc-pVTZ方法计算获得。通过对比前人计算结果,根据我们的程序包计算得到的电子-振动-自旋能级较以往的报道符合得较好,并能很容易扩展到更大的分子体系。     

具有D3h对称性构型的B2H6分子的杨-泰勒效应与能级分裂

文中依据杨-泰勒效应理论与配位场理论,利用群论和对称性分析的方法探讨了B2H6分子在具有D3h对称性构型的情况下,E e′系统的杨-泰勒效应及其相关问题。研究了B2H6分子的电子态与声子态以及活跃声子态,构建了B2H6分子的E e′杨-泰勒系统的电声耦合哈密顿量,利用么正平移变换将系统的哈密顿量分解为无声子激发部分与有声子激发部分之和,由此计算出了E e′杨-泰勒系统的基态与激发态及其能级。结果表明由于电声耦合作用的缘故,在E e′系统的势能面上形成了四个具有C2v对称性势阱。无论系统处在哪一个势阱中,系统初始的二重简并的能级都将发生分裂,因此杨-泰勒畸变导致系统能级的简并性完全被消除。文中利用群论又进一步探讨了系统的杨-泰勒畸变方向与能级分裂方式,发现系统的杨-泰勒畸变方向是D3h→C2v,能级的分裂方式为E′→A1+B2或者E″→A2+B1。     

具有D4h对称性构型的C42+分子的Jahn-Teller效应与能级分裂

依据量子理论与配位场理论,利用群论和对称性分析的方法探讨了C42+分子在具有D4h对称性构型时,E(b1g+b2g)系统的Jahn-Teller效应中的相关问题.研究了C42+分子的电子态与声子态的对称性及其活跃声子态,讨论了系统声子间的耦合与CG系数,构建了E(b1g+b2g)系统的电声耦合哈密顿量,利用幺正平移变换将系统变换到了无声子激发的空间中,由此计算出了系统无声子激发的基态与激发态及其能级,结果表明由于系统的电声耦合作用缘故,在系统的势能面上形成了四个对称性势阱.无论系统处在哪一个势阱中,在Jahn-Teller畸变之后,系统的二重简并的能级都将发生分裂,分裂后系统电子态的简并性完全被消除.文中利用群论又进一步探讨了系统的Jahn-Teller畸变方向及其基态对称性,发现系统将沿着D4h→D2h方向发生畸变.畸变后C24+分子的基态具有D2h群下的B1u对称性.     

CH3O (X2 E)中电子-振动-自旋耦合能级的理论计算

基于透热模型,采用量子化学从头计算法研究了CH₃O(X²E)自由基中电子-振动-自旋轨道相互作用.透热势能面通过CASPT2/cc-pVTZ方法计算获得.通过对比实验数据,计算得到的电子-振动-自旋能级较以往的报道获得了更精确的计算结果. 关键词： 透热模型 姜-泰勒效应 电子-振动-自旋耦合     

Pd☎ Ions In NaCl Single Crystal: EPR and Optical Studies

EPR and optical absorption of Pd centres in as grown NaCl single crystal arc reported. The EPR spectra show that palladium forms the Pd^? centre with d_x2-y2 wave function in the ground state. This centre formation and the accompanying distortion give rise to a superhyperfine interaction of the Pd^? ion with the nuclei of the four Cl^? ligands in the plane perpendicular to the C₄ symmetry axis. The results of the fitting of axial spin Hamiltonian parameters to the experimentally observed spectra give the following values at 12K: g∥ =2.85, g ⊥ ? 2.15, A ∥29.8 × 10^?4cm^?1, A ⊥ = 5.9 7imes; 10^?4cm^?1. When the temperature increases, lines are getting broader, their amplitude decreases and a single line with g-value of g= 2.38 at g = 1/3(g∥ ?2g⊥) appears, which demonstrates the known Jahn-Teller behaviour of d⁹ ions EPR spectra.     

Density-functional investigation of the excited state properties and the Jahn-Teller effect in [CrX6]3− (X=Cl−, Br−)

Summary The luminescence of [CrX₆]^3– X=Br^–, Cl^– has been studied through density functional theory (DFT) using both deMon and ADF codes. Multiplet energies⁴A₂,²E,⁴T₂, and⁴T₁ have been expressed as energies of non-redundant single determinants and calculated as in Ref. [1]. The influence of the metal ligand distance on the multiplet energies has been investigated. Of particular interest to this work is the Jahn-Teller effect distortion. We found that the system moves to a more stable geometry when the axial bond length is compressed and the equatorial one elongated in agreement with the experimental value.     

Jahn-Teller distortion motions as separatrices in PES

The topology of the pattern of intrinsic reaction coordinates and separatrices is investigated for 6-electron sigmatropic pericyclic rearrangements.It is demonstrated that the trajectories of nuclear motion involving HOMO-LUMO crossing are the separatrices of the basins of the chemical species involved. The special case of the Diels-Alder cycloaddition is analyzed.