Hyperfine interaction parameters and ground-state wavefunctions of vanadyl ion complexes

Using crystal field approach a theoretical estimate of the ground-state wavefunctions of vanadyl ion doped in various crystals have been made using ESR data and is found to bed _xy in our coordinate system with slight admixture of the excited states ,d _xz andd _yz. The hyperfine interaction parameterP and Fermi contact coupling parameterK have also been estimated for these vanadyl-doped crystals. Results agree with similar studies made earlier.     

Mott physics, sign structure, ground state wavefunction, and high-T c superconductivity

In this article I give a pedagogical illustration of why the essential problem of high-T _c superconductivity in the cuprates is about how an antiferromagnetically ordered state can be turned into a short-range state by doping. I will start with half-filling where the antiferromagnetic ground state is accurately described by the Liang-Doucot-Anderson (LDA) wavefunction. Here the effect of the Fermi statistics becomes completely irrelevant due to the no double occupancy constraint. Upon doping, the statistical signs reemerge, albeit much reduced as compared to the original Fermi statistical signs. By precisely incorporating this altered statistical sign structure at finite doping, the LDA ground state can be recast into a short-range antiferromagnetic state. Superconducting phase coherence arises after the spin correlations become short-ranged, and the superconducting phase transition is controlled by spin excitations. I will stress that the pseudogap phenomenon naturally emerges as a crossover between the antiferromagnetic and superconducting phases. As a characteristic of non Fermi liquid, the mutual statistical interaction between the spin and charge degrees of freedom will reach a maximum in a high-temperature ??strange metal phase?? of the doped Mott insulator.     

The study of magnetization of the spin system in the ground state

Within the framework of the effective-field theory with self-spin correlations and the differential operator technique, the ground state magnetizations of the biaxial crystal field spin system on the honeycomb lattices have been studied. The influences of the biaxial crystal field on the magnetization in the ground state have been investigated in detail.     

Anisotropic ESR parameters of Cu(II) complexes in solutions and dynamics of solvent coordination: use of “minimum linewidths”

The “minimum linewidths” seen in the ESR linewidths against temperature plots, the dependence of line widths on the⁶³Cu nuclear magnetic quantum numbers and the Hubbard relation provide sufficient number of equations to determine the anisotropic ESR parameters in the case of axially symmetric Cu(II) complexes even when unresolved hyperfine structures make contributions to linewidths. After testing the method by reanalysing the literature data on Cu(II) bis-acetylacetonate, it has been used to obtain the anisotropic ESR parameters in the case of bis-salicylaldehydate of Cu(II). Linewidth contributions from unresolved hyperfine structures associated with the¹H of coordinating CHCl₃ inferred in these studies, were confirmed by comparing the widths in CHCl₃ and CDCl₃ under ideal conditions. The temperature dependence of this contribution and the estimate of rate constant at room temperature (∼ 10¹⁰ s⁻¹) suggest that the coordinating solvent exchange is diffusion controlled.     

Perturbation allowed transitions in the infrared spectrum of 14ND3: determination of the K-dependent parameters in the ground state

ABSTRACT

Accurate values of the K-dependent constants ^{( i )} C, ^{( i )} D_K and ^{( i )} H_K in the ground state of ¹⁴ND₃, with i = s, a, have been determined for the first time thanks to the detections of ‘perturbation allowed’ transitions in the ν₁, ν₂, ν₃, ν₄ and 2ν₄ infrared bands. The rotation–inversion and inversion transitions from the literature, together with 7289 ground state combination differences from the infrared vibration–rotation–inversion transitions have been simultaneously analysed. The adopted rotation–inversion Hamiltonian includes distortion constants up to the eighth power and the Δk = ±3 and Δk = ±6 interaction terms. Precise values of the diagonal constants and of the Δk = ±3 interaction coefficients have been obtained. Accurate values of the ground state term values have been calculated for both s and a levels up to J = 21.     

ESR study of exchange coupled pairs in copper diethyldithiocarbamate—explanation of the low temperature hyperfine anomaly

A study of the hyperfine interaction in the ESR of Cu-Cu pairs in single crystals of copper diethyldithiocarbamate as a function of temperature has shown distinct differences in the hyperfine structure in the two fine structure transitions at 20 K, the spectrum not having the same hyperfine intensity pattern in the low field fine structure transition in contrast to that of the high field transition. The details of the structure of both the fine structure transitions in the 20 K spectrum have now been explained by recognizing the fact that the mixing of the nuclear spin states caused by the anisotropic hyperfine interaction affects the electron spin states | + 1 > and | −> differently. This has incidentally led to a determination of the sign ofD confirming the earlier model. The anomalous hyperfine structure is found to become symmetric at 77 K and 300 K. It is proposed that the reason for this lies in the dynamics of spin-lattice interaction which limits the lifetime of the spin states in each of the electronic levels | − 1 >, | 0 > and | + 1 > The estimate of spin-lattice relaxation time agrees with those indicated from other studies. The model proposed here for the hyperfine interaction of pairs in the electronic triplet state is of general validity.     

Electron spin resonance of the two-dimensional metallic state and the quantum Hall state in a Si/SiGe quantum well

We report electrically detected electron spin resonance (ESR) measurements of a high mobility two-dimensional (2D) electron system formed in a Si/SiGe quantum well, with millimeter wave in a high magnetic field . The negative ESR signal observed under an in-plane magnetic field gives direct evidence that the spin polarization leads to a resistance increase in the 2D metallic state. Suppression of spin decoherence was observed in the quantum Hall state at the Landau level filling factor ν=2. Strength of the nuclear magnetic field in the resonance is evaluated to be less than , much smaller than that reported for GaAs/AlGaAs heterostructures.     

The infinite-volume ground state of the Lennard-Jones potential

We consider a finite chain of particles in one dimension, interacting through the Lennard-Jones potential. We prove the ground state is unique, and approaches uniform spacing in the infinite-particle limit.Research supported in part by NSF grant MCS 78-01520.     

类硼离子基态的精细结构(英文)

以多电子精细结构哈密顿的球张量形式为基础,借助不可约张量理论,建立了类硼离子基态精细结构能量的解析表达式.完成了所有角向积分和自旋求和计算,使精细结构能量表示为若干个径向积分之和.在此基础上计算了类硼体系(Z=5~8)基态精细结构能量,计算结果与实验数据符合得较好.     

钾原子基态的定量证明

用原子实模型简化钾原子的哈密顿,把原子实极化和轨道贯穿视为微扰,用微扰法计算了钾原子的能量,定量证明了钾原子的基态是4s态．     

MnFe2O4晶体的基态能级和零场分裂参量

由不可约张量理论构成一个3d4/3d6离子三角(C3V)对称的晶体场和自旋-轨道相互作用哈密顿矩阵,由这个晶体场和自旋-轨道相互作用哈密顿矩阵被完全对角化后能够求出MnFe2O4晶体中的Fe2+离子的电子顺磁共振零场分裂参量D和F-a,计算了低自旋态(3L态)对电子顺磁共振零场分裂参量(D,F-a)的贡献.结果显示低自旋3L态对电子顺磁共振的零场分裂参量的贡献是较强的.理论计算的结果与实验值是相符的.     

能量公设与热力学系统独立状态参量的选取

论述了能量公设,并得到能量状态的一般表达式由各种能位形式组成,每一种能位形式可表示为一个强度量和一个广延量的乘积．由此,提出了热力学系统独立状态参量的数目由能位数目来决定,并且每一个独立状态参量只能是组成同一能位的强度量ξi和广延量ξi中的一个．     

Modified hypernetted-chain equation for the ground state of Bose fluids

Summary The modified hypernetted-chain equation is used to study the ground state of Bose fluids in the Jastrow approximation. We test the equation for different forms of the pair interaction and of the Jastrow pseudopotential and in all cases the energy of⁴He is given with an error not larger than 0.1 K at all densities. The effect of a triplet term in the wavefunction is also studied.

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Riassunto L'equazione integrale HNC modificata è applicata allo studio dello stato fondamentale di un fluido di Bose nell'approssimazione di Jastrow per diverse espressioni della interazione binaria e forme diverse della correlazione di Jastrow. In tutti i casi l'energia per⁴He è calcolata con un errore non superiore a 0.1 K a tutte le densità. Si considera inoltre l'effetto di una correlazione a tre corpi nella funzione d'onda.

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Резюме модифицированное уравнение цепочки используется для исследования основного состояния Ъозе-жидкости в приближении Ястрова. Мы проверяем уравнение для различных форм парного взаимодействия и псевдопотенциала Ястрова. Во всех случаях приводится энергия⁴He с погрешностью не более, чем 0.1 K для всех плотностей. Также исследуется влияине триплетного члена на волновую функцию.

     

中性碳原子基态关联效应的多体理论计算

应用原子多体理论对开壳层原子中电子关联效应的有效哈密顿量及波算符的Goldston图进行了分析,在此基础上得到了计算有效哈密顿量的简单方法;以HFS模型为零级近似对中性碳原子基态的关联效应进行了计算并通过与实验结果及其他文献基于HF模型进行的计算相比较,得到了令人满意的结论。     

原子基态求法的探讨

在最外层电子分布中,d壳层出现了抢电子的现象,它造成原子基态求法的困难.同时应用一般方法求出少数原子基态与理论不符,有些教材对这几种原子基态提出3种不同看法.本文就这两种现象进行了分析和说明.     

Hyperfine anomaly for the ground state of 9Be+

The Fermi contact parameter which represents hyperfine structure (hfs) has been accurately calculated for the ground state of the ⁹Be⁺ ion in a previous paper. In the present paper, the calculated parameter is compared with a high precision measurement to derive the hfs anomaly (the Bohr-Weisskopf effect), which is caused by nuclear magnetization distribution. The obtained hfs anomaly shows a satisfactory agreement with the result of a nuclear shell model calculation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Site-selective electron nuclear double resonance in the exchange-narrowed regime of the ESR in conducting solids

Electron nuclear magnetic double resonance on conduction electrons reveals the hyperfine interaction hidden by the fast electron spin exchange. We used the Overhauser shift technique to investigate the electron spin density of the conduction band of gallium oxide, beta-Ga(2)O(3). Due to the monoclinic structure, the conduction band of beta-Ga(2)O(3) is anisotropic and it is dominated by contributions from the two nonequivalent Ga sites. The large quadrupole couplings of the two gallium isotopes (69)Ga and (71)Ga (both with I = 3/2) are completely resolved in our double-resonance experiments. This resolved quadrupole interaction allows the determination of the electric field gradients at both gallium sites with high precision and high sensitivity. The resolved quadrupole splitting is the key to the site-selected determination of the hyperfine interaction. The concepts behind these double-resonance techniques are rather general and should be applicable in similar semiconductor systems.     

同调谐振子参数与基态能量的关系

采用升降算符方法研究了同调谐振子(包括一维谐振子)定态薛定谔方程的严格解,详细讨论了谐振子参量不同取值范围形成不同基态能量的关系.对于有关文献的一些欠完善的提法给予了分析和澄清 关键词： 同调谐振子 升算符 降算符 基态能量     

Hartree-Fock variational bounds for ground state energy of chargeless fermions with finite magnetic moment in the presence of a hard core potential: A stable ferromagnetic state

We use different determinantal Hartree-Fock (HF) wave functions to calculate true variational upper bounds for the ground state energy of N spin-half fermions in volume V ₀, with mass m, electric charge zero, and magnetic moment μ, interacting through magnetic dipole-dipole interaction. We find that at high densities when the average interparticle distance r ₀ becomes small compared to the magnetic length r _m ≡ 2mμ²/ħ², a ferromagnetic state with spheroidal occupation function n _↑(), involving quadrupolar deformation, gives a lower upper bound compared to the variational energy for the uniform paramagnetic state or for the state with dipolar deformation. This system is unstable towards infinite density collapse, but we show explicitly that a suitable short-range repulsive (hard core) interaction of strength U ₀ and range a can stop this collapse. The existence of a stable equilibrium high density ferromagnetic state with spheroidal occupation function is possible as long as the ratio of coupling constants Γ_cm ≡ (U ₀ a ³/μ²) is not very small compared to 1.