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Thermodynamic functions of ZrW_2O_8 from its heat capacity

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Science China(physics,Mechanics & Astronomy) 2012年第4期55卷 563-567页

作者： Ji FengMin DAI XianXi STEVENS R GOATES J B College of Sciences Ningbo University of TechnologyNingbo 315211China research group of quantum statistics and methods of theoretical physics Department of PhysicsFudan University Shanghai 200433China Department of Chemistry Brigham Young UniversityProvoUT 84602USA

It is interesting to maximize the amount of information we can obtain from one experiment on a single sample. In obtaining all the thermodynamic properties of some materials from their experimental heat capacity data only, we aim to get the tempera- ture-independent energy spectrum. However, all the practical measured energy spectra depend on the temperature of experi- ments. One promising method to obtain the temperature-independent energy spectrum is to solve the so-called specific heat-phonon spectrum inversion （SPI） problem. Here we show, by developing a new practical solution method of SPI, the phonon spectrum of the negative thermal expansion material ZrW208 is obtained. This phonon spectrum is tempera- ture-independent and almost method independent. Hence all the thermodynamic properties of ZrW208, such as thermodynamic potential, entropy, Helmholtz free energy, etc. are obtained by heat capacity only.

关键词： holographic studies instability problems specific heat-phonon spectrum inversion problem DMF method

Entanglement and Other Nonclassical Properties of Two Two-Level Atoms Interacting with a Two-Mode Binomial Field: Constant and Intensity-Dependent Coupling Regimes

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Communications in theoretical physics 2015年第10期64卷 439-446页

作者： M.K.Tavassoly H.Hekmatara Atomic and Molecular group Faculty of Physics Yazd University Photonic research group Engineering Research Center Yazd University The Laboratory of quantum Information Processing Yazd University

In this paper, we consider the interaction between two two-level atoms and a two-mode binomial field with a general intensity-dependent coupling regime. The outlined dynamical problem has explicit analytical solution, by which we can evaluate a few of its physical features of interest. To achieve the purpose of the paper, after choosing a particular nonlinearity function, we investigate the quantum statistics, atomic population inversion and at last the linear entropy of the atom-field system which is a good measure for the degree of entanglement. In detail, the effects of binomial field parameters, in addition to different initial atomic states on the temporal behavior of the mentioned quantities have been analyzed. The results show that, the values of binomial field parameters and the initial state of the two atoms influence on the nonclassical effects in the obtained states through which one can tune the nonclassicality criteria *** intensity-dependent coupling function equal to 1 reduces the results to the constant coupling case. By comparing the latter case with the nonlinear regime, we will observe that the nonlinearity disappears the pattern of collapse-revival phenomenon in the evolution of Mandel parameter and population inversion(which can be seen in the linear case with constant coupling), however, more typical collapse-revivals will be appeared for the cross-correlation function in the nonlinear case. Finally, in both linear and nonlinear regime, the entropy remains less than(but close to) 0.5. In other words the particular chosen nonlinearity does not critically affect on the entropy of the system.

关键词： Jaynes–Cummings model atom-field interaction two-m

Nonplanar Ion-Acoustic Solitons in Electron-Positron-Ion quantum Plasmas

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Chinese physics Letters 2009年第4期26卷 150-153页

作者： S. A. Khan S. Mahmood Arshad M. Mirza Department of physics COMSATS Institute of Information Technology Islamabad Pakistan National Centre for physics Quaid-i-Azam University Campus Islamabad Pakistan Department of physics Government College Bagh AJK Pakistan theoretical Plasma physics Division PINSTECH PO Nilore Islamabad Pakistan theoretical Plasma physics group Department of Physics Quaid-i-Azam University Islamabad 45320 Pakistan

The propagation of nonplanar quantum ion-acoustic solitary waves in a dense, unmagnetized electron-positronion （e-p-i） plasma are studied by using the Korteweg-de Vries （KdV） model. The quantum hydrodynamic （QHD） equations are used taking into account the quantum diffraction and quantum statistics corrections. The analytical and numerical solutions of KdV equation reveal that the nonplanar ion-acoustic solitons arc modified significantly with quantum corrections and positron concentration, and behave differently in different geometries.

关键词： SOLITONS ION acoustic waves quantum theory PLASMA (Ionized gases) ELECTRONS POSITRONS KORTEWEG-de Vries equation EQUATIONS -- Numerical solutions

Power-law scalings in weakly-interacting Bose gases at quantum criticality

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Frontiers of physics 2022年第6期17卷 235-241页

作者： Ming-Cheng Liang Zhi-Xing Lin Yang-Yang Chen Xi-Wen Guan Xibo Zhang International Center for quantum Materials School of PhysicsPeking UniversityBeijing 100871China Collaborative Innovation Center of quantum Matter Beijing 100871China State Key Laboratory of Magnetic Resonance and Atomic and Molecular physics Wuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China Institute of Modern physics Northwest UniversityXi'an 710127China Department of theoretical physics Research School of Physics and EngineeringAustralian National UniversityCanberra ACT 0200Australia Beijing Academy of quantum Information Sciences Beijing 100193China

Weakly interacting quantum systems in low dimensions have been investigated for a long time,but there still remain a number of open questions and a lack of explicit expressions of physical properties of such *** this work,we find power-law scalings of thermodynamic observables in low-dimensional interacting Bose gases at quantum *** present a physical picture for these systems with the repulsive interaction strength approaching zero;namely,the competition between the kinetic and interaction energy scales gives rise to power-law scalings with respect to the interaction strength in characteristic thermodynamic *** prediction is supported by exact Bethe ansatz solutions in one dimension,demonstrating a simple 1/3-power-law scaling of the critical entropy per *** method also yields results in agreement with a non-perturbative renormalization-group computation in two *** results provide a new perspective for understanding many-body phenomena induced by weak interactions in quantum gases.

关键词： power-law scaling quantum criticality Bose gases weak interaction non-perturbative methods

Zero Temperature Numerical Studies of Multiband Lattice Models of Strongly Correlated Electrons

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Communications in Computational physics 2006年第4期1卷 575-615页

作者： Yong-Qiang Wang Hai-Qing Lin J.E.Gubernatis Department of physics and the Institute of theoretical physics The Chinese University of Hong KongShatinN.T.Hong Kong SAR theoretical Division Los Alamos National LaboratoryLos AlamosNM 87545 USA

Relative to single-band models,multiband models of strongly interacting electron systems are of growing interest because of their wider range of novel phenomena and their closer match to the electronic structure of real *** this brief review we discuss the physics of three multiband models(the three-band Hubbard,the periodic Anderson,and the Falicov-Kimball models)that was obtained by numerical simulations at zero *** first give heuristic descriptions of the three principal numerical methods(the Lanczos,the density matrix renormalization group,and the constrainedpath Monte Carlo methods).We then present generalized versions of the models and discuss the measurables most often associated with ***,we summarize the results of their ground state numerical *** each model was developed to study specific phenomena,unexpected phenomena,usually of a subtle quantum mechanical nature,are often *** as often,the predictions of the numerical simulations differ from those of mean-field theories.

关键词： Lanczos method density matrix renormalization group constrained-path Monte Carlo three-band Hubbard model periodic Anderson model Falicov-Kimball model

Review of Feynman’s Path Integral in quantum statistics:from the Molecular Schrödinger Equation to Kleinert’s Variational Perturbation Theory

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Communications in Computational physics 2014年第4期15卷 853-894页

作者： Kin-Yiu Wong Department of physics High Performance Cluster Computing CentreInstitute of Computational and Theoretical StudiesHong Kong Baptist University224 Waterloo RoadKowloon TongHong Kong Institute of research and Continuing Education Hong Kong Baptist University(Shenzhen)

Feynman’s path integral reformulates the quantum Schrödinger differential equation to be an integral *** has been being widely used to compute internuclear quantum-statistical effects on many-body molecular *** this Review,the molecular Schrödinger equation will first be introduced,together with the BornOppenheimer approximation that decouples electronic and internuclear *** effective semiclassical potentials,e.g.,centroid potential,which are all formulated in terms of Feynman’s path integral,will be discussed and *** semiclassical potentials can be used to directly calculate the quantum canonical partition function without individual Schrödinger’s energy *** a result,path integrations are conventionally performed with Monte Carlo and molecular dynamics sampling *** complement these techniques,we will examine how Kleinert’s variational perturbation(KP)theory can provide a complete theoretical foundation for developing non-sampling/non-stochastic methods to systematically calculate centroid *** enable the powerful KP theory to be practical for many-body molecular systems,we have proposed a new path-integral method:automated integrationfree path-integral(AIF-PI)*** to the integration-free and computationally inexpensive characteristics of our AIF-PI method,we have used it to perform ab initio path-integral calculations of kinetic isotope effects on proton-transfer and RNA-related phosphoryl-transfer chemical *** computational procedure of using our AIF-PI method,along with the features of our new centroid path-integral theory at the minimum of the absolute-zero energy(AMAZE),are also highlighted in this review.

关键词： Feynman’s path integral Kleinert’s variational perturbation theory Schrödinger’s equation quantum statistics centroid potential energy quantum tunneling zero-point energy isotope effects

Coupled Electromagnetic Circuits and Their Connection to quantum Mechanical Resonance Interactions and Biorhythms

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Open Journal of Biophysics 2013年第4期3卷 253-274页

作者： W.Ulmer G.Cornelissen research group Radiation physics University of ZuerichMax-Planck-Institute of PhysicsGottingenGermany University of Minneapolis MinneapolisUSA

The existence of specific biorhythms and the role of geomagnetic and/or solar magnetic activities are well-established by appropriate correlations in chronobiology. From a physical viewpoint, there are two different accesses to biorhythms to set up connections to molecular processes: quantum mechanical perturbation theoretical methods and their resonance dominators to characterize specific interactions between constituents. These methods permit the treatment of molecular processes by circuits with characteristic resonances and “beat-frequencies”, which result from primarily fast physical processes. As examples, the tunneling processes between DNA base pairs (H bonds), the ATP decomposition and the irradiation of tumor cells are accounted for.

关键词： Electromagnetic Circuits Biorhythms quantum Mechanical Resonance Interactions

Analytical approximations to a generalized forced damped complex Duffing oscillator:multiple scales method and KBM approach

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Communications in theoretical physics 2023年第2期75卷 18-27页

作者： Weaam Alhejaili Alvaro H Salas S A El-Tantawy Department of Mathematical Sciences College of SciencePrincess Nourah bint Abdulrahman UniversityP.O.Box 84428Riyadh 11671Saudi Arabia Department of Mathematics and statistics Universidad Nacional de ColombiaFIZMAKO Research GroupColombia Department of physics Faculty of SciencePort Said UniversityPort Said 42521Egypt research Center for physics(RCP) Department of PhysicsFaculty of Science and ArtsAl-MikhwahAl-Baha UniversitySaudi Arabia

In this investigation,some different approaches are implemented for analyzing a generalized forced damped complex Duffing oscillator,including the hybrid homotopy perturbation method(H-HPM),which is sometimes called the Krylov-Bogoliubov-Mitropolsky(KBM)method and the multiple scales method(MSM).All mentioned methods are applied to obtain some accurate and stable approximations to the proposed problem without decoupling the original *** obtained approximations are discussed graphically using different numerical values to the relevant ***,all obtained approximate solutions are compared with the 4thorder Runge-Kutta(RK4)numerical *** maximum residual distance error(MRDE)is also estimated,in order to verify the high accuracy of the obtained analytic approximations.

关键词： complex Duffing oscillators forced damped complex oscillator multiple scales method KBM method

中心对称且具有非简单空间群结构的晶体中可调控的Dzyaloshinskii-Moriya相互作用

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Science Bulletin 2023年第11期68卷 1113-1118,M0003页

作者：张中义秦盛山臧佳栋方辰胡江平张富春 Beijing National Laboratory for Condensed Matter physics and Institute of physics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China School of physics Beijing Institute of TechnologyBeijing 100081China Kavli Institute for theoretical Sciences CAS Center for Excellence in Topological Quantum ComputationUniversity of Chinese Academy of SciencesBeijing 100190China Department of physics and Astronomy University of New HampshireDurham 03824USA Materials Science Program University of New HampshireDurham 03824USA South Bay Interdisciplinary Science Center Dongguan 523808China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

非中心对称材料中存在的Dzyaloshinskii-Moriya(DM)相互作用,可以导致新颖的自旋纹理和奇异的手性物理现象.而如果能在中心对称的晶格中发现DM相互作用,这将可以大大丰富实现上述新奇物理的材料体系.本文发现中心对称的且遵循非简单空... 详细信息

非中心对称材料中存在的Dzyaloshinskii-Moriya(DM)相互作用,可以导致新颖的自旋纹理和奇异的手性物理现象.而如果能在中心对称的晶格中发现DM相互作用,这将可以大大丰富实现上述新奇物理的材料体系.本文发现中心对称的且遵循非简单空间群结构的巡游电子体系可以作为实现DM相互作用的新平台.以遵循P4/nmn空间群的晶格为例,作者展示了在该中心对称晶格中,由巡游电子导致的Ruderman-Kittel-Kasuya-Yosida(RKKY)相互作用中包含DM相互作用、Heisenberg交换相互作用和Kaplan-Shekhtman-Entin-wohlman-Aharony(KSEA)相互作用.在这其中,DM相互作用的DM矢量的方向取决于实空间中磁性原子的位置,DM相互作用的强度取决于动量空间中费米面的位置.该晶格体系中磁性相互作用的多样性,源于非简单空间群对称性保证的实空间中位置依赖的在位点群和倒空间中动量依赖的电子结构.本研究揭示了非简单空间群对称性如何影响晶体中的磁性,表明非简单空间群晶格体系是设计磁性相互作用非常有前景的平台.

关键词：巡游电子中心对称物理现象动量空间费米面磁性原子