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A Rigorous Investigation on the Ground State of the Penson—Kolb Model

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Communications in Theoretical Physics 2003年第5期39卷 607-612页

作者： YANGKai-Hua tianguang-shan HANRu-Qi InstituteofMicroelectronics PekingUniversityBeijing100871China SchoolofPhysics PekingUniversityBeijing100871CHina SchoolofPhysics PekingUniversityBeijing100871CHina InstituteofMicroelectronics PekingUniversityBeijing100871China

By using either numerical calculations or analytical methods, such as the bosonization technique, the ground state of the Penson-Kolb model has been previously studied by several groups. Some physicists argued that, as far as the existence of superconductivity in this model is concerned, it is canonically equivalent to the negative-U Hubbard ***, others did not agree. In the present paper, we shall investigate this model by an independent and rigorous approach. We show that the ground state of the Penson-Kolb model is nondegenerate and has a nonvanishing overlap with the ground state of the negative-U Hubbard model. Furthermore, we also show that the ground states of both the models have the same good quantum numbers and may have superconducting long-range order at the same momentum q ＝ 0. Our results support the equivalence between these models.

关键词：超导电性 Penson-Kolb模型强相关电子系统 “负-U Hubbard模型”

Effect of Lattice Distortion on Charge Order in Manganites at Doping x=0.5

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Communications in Theoretical Physics 2005年第1期43卷 179-186页

作者： WANGHai-Long tianguang-shan LINHai-Qing SchoolofPhysics PekingUniversityBeijing100871China SchoolofPhysics PekingUniversityBeijing100871China／／DepartmentofPhysicstheChineseUniversityofHongKongShatinN.T.HongKongChina

In the present paper, we continue our investigation on the antiferromagneticorigin of the charge order observed in the halt-doped manganese. By introducing aSu-Schrieffer-Heeger (SSH) type of perturbation interaction to the double-exchange Hamiltonian, wecalculate again its ground-state phase diagram at Glling x = 0.5 by the unrestricted real-spaceHartree-Fock approximation method. We find that, as the SSH electron-phonon interaction increases,the charge order parameter decreases to zero rapidly but the CE-type antiferromagnetic order becomesmore stable. In other words, the charge order is much more fragile than the CE-type or theNeel-type antiferromagnetic orders under the electron-phonon perturbation. These results support theproposed theory in the recent publications that the charge order in these systems is induced by theantiferromagnetic correlations.

关键词： manganites charge ordered phases antiferromagnetic correlation

Charge Ordering Due to Antiferromagnetic Correlation in Quarter-Filled Manganites

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Communications in Theoretical Physics 2004年第3X期42卷 475-480页

作者： WANGHai-Long tianguang-shan LINHai-Qing SchoolofPhysics PekingUniversityBeijing100871China DepartmentofPhysics ChineseUniversityofHongKongShatinN.T.HongKongChina

In the present paper, we study the zero-temperature phase diagram of the doped perovskite manganitesat filling x = 0.5 by the real-space Hartree-Fock approximation method. Our purpose is to resolve a controversialissue arising recently on the origin of the charge ordered phases in these systems. We find that the antiferromagneticsuperexchange interaction between the localized spins plays the central role in producing the concerned phases. Ourresults confirm some speculations on this issue.

关键词：反铁磁相关性水锰矿哈特里-福克近似理论巨磁阻效应相位图磁相结构

Effects of Conduction Electron Band Structure on Transport of Quantum Dot Systems

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Chinese Physics Letters 2003年第5期20卷 717-720页

作者： YANGKai-Hua SONGBo tianguang-shan WANGYu-Peng HANRu-shan HANRu-Qi InstituteforMicroelectronics PekingUniversityBeijing100871 TechnicalInstituteofPhysicsandChemistry ChineseAcademyofSciencesBeijing100080 SchoolofPhysics PekingUniversityBeijing100871 InstituteofPhysicsandCenterforCondensedMatterPhysics ChineseAcademyofSciencesBeijing100080

We study the effects of the energy band structure of conduction-electron on the transport properties of an interacting quantum dot system. By applying the nonequilibrium Keldysh Green function technique, we show that the finite width of electron band in leads causes the negative differential conductance in some regions of the applied voltage. We also show that the van Hove singularities in the density of states of conduction-electron do not qualitatively change the differential conductance of the system, and hence can be safely ignored. Therefore, the wide band approximation used in the previous investigations is partially justified.

关键词：量子通信体系相互作用电子传输电子结构量子点

基于Chirp数据和Biot-Stoll模型反演南海北部陆坡海底表层沉积物物理性质

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海洋学报 2020年第3期42卷 72-82页

作者：周庆杰李西双刘乐军刘洋廷高珊周航王景强李天光自然资源部第一海洋研究所海洋沉积与环境地质国家海洋局重点实验室山东青岛266061 青岛海洋科学与技术试点国家实验室海洋地质过程与环境功能实验室山东青岛266061 青岛海洋科学与技术试点国家实验室海洋矿产资源评价与探测技术功能实验室山东青岛266071

浅地层剖面是基于声学信号(频率在几百至几千赫兹)在沉积物中的传播得到可反映沉积地层结构的数据,海底反射系数与沉积物物理性质密切相关。Biot-Stoll声波传播理论模型可以预测海底沉积物的物理性质,构建反射系数等声学参数与物理参数... 详细信息

浅地层剖面是基于声学信号(频率在几百至几千赫兹)在沉积物中的传播得到可反映沉积地层结构的数据,海底反射系数与沉积物物理性质密切相关。Biot-Stoll声波传播理论模型可以预测海底沉积物的物理性质,构建反射系数等声学参数与物理参数之间的关系,但在不同的海域采用不同的参数所获得的效果不同。为此,本文基于南海北部陆坡海底表层沉积物的实测物理参数,利用BiotStoll模型建立研究区海底反射系数和沉积物物理性质之间的关系,结果表明模型计算值与样品实测值吻合度总体较好,偏差在0.1%~4.9%之间,并建立了频率3.5 kHz时海底反射系数与沉积物孔隙度、密度、平均粒径之间的关系方程,且方程拟合度较高,可决系数R2均大于0.99。在对典型Chirp剖面数据计算其海底反射系数的基础上,反演了海底表层沉积物的孔隙度、密度、颗粒平均粒径等物理性质,其中反演孔隙度、密度、平均粒径与实测孔隙度、密度、平均粒径相对误差均小于5%,结果与实测值基本相符,表明该反演方法在南海北部陆坡区的应用是可行的。

关键词： Chirp浅剖数据 Biot-Stoll模型海底反射系数沉积物物理性质南海北部陆坡