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1. chinaXiv:201607.00046 [pdf]

Exact Solution for Three-Dimensional Ising Model

Zhang, Degang
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Three-dimensional Ising model in zero external field is exactly solved by operator algebras, similar to the Onsager's approach in two dimensions. The partition function of the simple cubic crystal imposed by the periodic boundary condition along both $(0 1 0)$ and $(0 0 1)$ directions and the screw boundary condition along the $(1 0 0)$ direction is calculated rigorously. In the thermodynamic limit an integral replaces a sum in the formula of the partition function. A order-disorder transition in the infinite crystal occurs at a temperature $T=T_c$ determined by the condition: $\sinh\frac{2J}{k_BT_c}\sinh\frac{2(J_1+J_2)}{k_BT_c}=1$, where $(J_1 J_2 J)$ are the interaction energies in three directions, respectively. The analytical expressions for the internal energy and the specific heat are also given. It is also shown that the thermodynamic properties of 3D Ising model with $J_1=J_2$ are connected to those in 2D Ising model with the interaction energies $(J_1 J_{2D})$ by the relation $(\frac{J_{2D}}{k_BT})^*=(\frac{J}{k_BT})^*-\frac{J_1}{k_BT}$, where $x^*=\frac{1}{2}{\rm ln coth} x={\rm tanh}^{-1}(e^{-2x})$.

submitted time 2019-09-12 Hits4442Downloads1226 Comment 0

2. chinaXiv:201909.00120 [pdf]

西宁盆地4种草本和灌木植物降盐效应试验研究

李淑霞; 刘亚斌; 钟鹏; 余冬梅; 胡夏嵩; 杨幼清
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

以西宁盆地长岭沟流域自建试验区为研究区,筛选出适宜当地气候条件下生长的2种灌木植物柠条锦鸡儿(Caragana korshinskii Kom.)、霸王〔Zygophyllum xanthoxylon (Bunge) Maxim.〕和2种草本植物细茎冰草(Agropyron trachycaulum cv. Slender)、紫花苜蓿(Medicago sativa Linn.)作为试验供试种,在试验区对4种植物采用单一种植和组合种植方式,探讨2种种植条件下植物根系在边坡地表以下垂直方向土体中K+、Ca2+、Na+、Mg2+、SO42-、Cl-、HCO3-、CO32-等8种易溶盐离子含量及其变化特征,评价了区内2种草本和2种灌木植物降低边坡土体盐分的能力。结果表明:单一种植细茎冰草、紫花苜蓿、柠条锦鸡儿、霸王对边坡土体中SO42-、Ca2+、Na+具有显著降低作用,草本与灌木组合Ⅰ(柠条锦鸡儿+紫花苜蓿+细茎冰草组合)和草本与灌木组合Ⅱ(霸王+紫花苜蓿+细茎冰草组合)对边坡土体中SO42、Ca2+、Mg2+、K+、Na+表现出显著降低作用;紫花苜蓿的降盐效果相对较为显著、其次为柠条锦鸡儿和细茎冰草,霸王的降盐效果不及前者显著;草本与灌木组合Ⅱ的降盐效果相对显著于草本与灌木组合Ⅰ。

submitted time 2019-09-09 From cooperative journals:《干旱区研究》 Hits1386Downloads18 Comment 0

3. chinaXiv:201907.00026 [pdf]

Exact Solution of Quantum Rabi Model

Degang Zhang
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Quantum Rabi model is exactly solved by employing the parameter-dependent unitary transformation method in the Bargmann space. The complete energy spectrum consists of two double-fold sub-energy spectra. The eigenvalue is determined by the parameter in the unitary transformation, which satisfies a highly nonlinear equation. Such the energy spectrum completely coincides with that obtained in the occupation number representation [D. Zhang, chinaXiv:201708.00168].

submitted time 2019-07-31 Hits1291Downloads63 Comment 0

4. chinaXiv:201907.00002 [pdf]

The Change of the Electron Clouds of Ions in Cuprate Superconductor CaCuO2: A First-Principles Investigation of the Electron-Pairing

Tiege Zhou
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

P. W. Anderson raised an important question in 2007: Is There Glue in Cuprate Superconductors? The author believes that the change of the electron clouds of ions is the glue in cuprate superconductors. The change of the electron clouds of the ions in the parent structure of the layered high-temperature superconductors CaCuO2 has been studied by the first-principles calculations. The electron clouds of Cu2+ and O2- ions change obviously under electric fields. It is also found, for the first time, the characteristic frequencies of the change of the electron clouds are 250 meV, 360 meV, and 100 meV, respectively, for the modes observed. The frequencies are low and close to that of lattice vibrations, indicating the change of the electron cloud of ions can be the electron-pairing medium in cuprate superconductors.

submitted time 2019-07-02 Hits278Downloads116 Comment 0

5. chinaXiv:201906.00024 [pdf]

Characteristic frequency of the orbital fluctuation in the unconventional iron-based superconductor BaFe2As2: A TDDFT investigation of the electron pairing mechanism

Tiege Zhou
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

It is proposed that the electron-pairing medium of the iron-based superconductors may be the orbital fluctuation of the transition metal ions. But the characteristic frequency of the orbital fluctuation has not been given. For the first time, the author has calculated the real-time evolution of the electron clouds of transition metal ions in BaFe2As2 under excitations by the time-dependent density functional theory (TDDFT). There are different modes of fluctuations. The characteristic frequencies are 150 meV, 160 meV, 250 meV, and 200 meV, respectively, for the modes the author observed. The results are unexpected, because the general view is that the change of the electron density is very quick, and the frequency is much higher than the lattice vibration. The frequencies the author obtained are close to that of the lattice vibration in conventional superconductors at normal and high pressures, indicating the orbital (or electron cloud) fluctuation can by the electron pairing medium. Based on the calculation results, the author proposed a new electron pairing mechanism.

submitted time 2019-06-13 Hits275Downloads135 Comment 0

6. chinaXiv:201905.00050 [pdf]

基于单极感应问题的多极感应实验

张学亮
Subjects: Physics >> Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics

针对单极感应之谜,本文注意到磁力线是闭合线,利用洛伦茨力概念首先证明N与M两种对立观点都能够合理解释自法拉第时期以来典型的、有较大影响的单极感应实验。并采用等效电路和比较简明的方法推演出单极感应实验测量回路中感应电动势的一般表达式,说明单极感应问题至今未果的原因是实验采用的轴对称磁体外围磁场特殊的对称性分布结构,且分布结构不随磁体旋转而改变造成的。也说明单极感应实验本身无法解决单极感应问题。介绍了一种多极感应实验方案与实验结果,结合实验磁体外围磁场分布状况,同样用N与M两种观点对照分析了实验结果,得出了法拉第与韦伯当年的单极感应实验测量回路中的感应电动势是由磁体外相对于实验室参照系静止的线段产生的结论,该结论与M观点的结论一致。

submitted time 2019-05-08 Hits2669Downloads218 Comment 0

7. chinaXiv:201904.00095 [pdf]

Real-Time Evolution of the Electron Clouds of Transition Metal Ions: Electron-Pairing Medium of Unconventional High Temperature Superconductors

Tege Zhou
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

The electron-pairing mechanism in unconventional high temperature superconductors (HTS) has not been resolved. The author proposed that the electron-pairing medium of unconventional HTS is the change of the electron clouds of transition metal ions, which is analogous to the lattice vibration in conventional superconductors. Real-time evolution of the electron clouds of transition metal ions under excitations in La2Fe2As2O2, FeSe sheet, Fe2KSe2, CaCuO2, and HgBa2Ca2Cu3O8 was calculated by the time-dependent density functional theory (TDDFT). The characteristic frequency is about 90-250 meV, which is equivalent to the lattice vibration frequencies, showing that the change of the electron clouds of the transition metal ions can be the electron-pairing medium in unconventional HTS.

submitted time 2019-04-24 Hits872Downloads237 Comment 0

8. chinaXiv:201802.00685 [pdf]

An Explanation of the Interactions between Waves and Electrons: Discussion of Electromagnetic Fields

Weiye Xu
Subjects: Physics >> The Physics of Elementary Particles and Fields

The interactions between waves and electrons are the basis of vacuum tubes and particle accelerators. In order to further understand the interactions, we proposed a new electromagnetic model. In this model, the photon is composed of two elementary particles – ephoton and mphoton, which are the basic particles that form the electric fields and magnetic fields, respectively. There are many ephotons around the electrons and the electrons can absorb the ephotons. The proposed electromagnetic model can well explain the electromagetic phenomena and the interactions between waves and electrons.

submitted time 2019-04-12 Hits3191Downloads1127 Comment 0

9. chinaXiv:201905.00054 [pdf]

多体多自由度量子隐形传态的张量表示

征夏明
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

[目的] 找到一种最普遍情况下量子隐形传态的一般表示及代数结构。 [方法] 归纳推理与演绎推理,利用多项式相乘与张量积之间的等价性发现一般规律。 [结果] 将多体单自由度或单体多自由度的量子隐形传态推广至多体多自由度,以及混合态。 [局限] 无法推广至连续谱量子态。 [结论] 预言多体多自由度单次量子隐形传态的存在,并包含了已被实验证实的所有特殊情况。

submitted time 2019-04-11 Hits4043Downloads215 Comment 0

10. chinaXiv:201905.00053 [pdf]

纠缠态判据与高阶张量可分性的充分必要条件

征夏明
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

[目的] 找到高阶张量和纯态可写成多个低阶张量乘积的充要条件。 [方法] 类比推理、归纳推理,从多元函数可分离变量的充要条件出发,利用与矩阵的代数余子式的性质,最后得到一般的结论。 [结果] 证明定理及其多个等价形式。 [局限] 不适用于混合态。 [结论] 纯态是否是纠缠态的充要条件。

submitted time 2019-04-11 Hits3753Downloads178 Comment 0

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