The electronic viewpoint on the morphology of the microclusters

A possible role of the electron interaction in the morphology of the microcluster is studied. Highly symmetrical configuration leads to highly degenerated single-particlelevels. They are preferable for the emergence of the magnetic polarization (the Hundtendency). On the other hand, the splitting of the degenerated Fermi level due to the lowering of the symmetry sometimes reduces the ground state energy (the Jahn-Teller tendency). The conflict of these two tendencies is investigated by a simple model.On leave from Department of Physics, Faculty of Science, Kyoto University, Kyoto, 606 Japan     

二维Sinai台球系统的量子混沌研究

研究了二维Sinai台球系统的经典与量子的对应关系,运用定态展开法和Gutzwiller的周期轨道理论对Sinai台球系统的态密度经傅里叶变换得到的量子长度谱进行分析,并把量子长度谱中峰的位置与其所对应的经典体系的周期轨道长度做对比,发现两者之间存在很好的对应关系.观察到了一些量子态局域在短周期轨道附近形成量子scarred态或量子superscarred态.还研究了同心与非同心Sinai台球系统的能级最近邻间距分布,发现同心Sinai台球系统是近可积的,非同心Sinai台球系统在θ=3π/8下,随两中心间距离的增加,能级最近邻间距分布将由近可积向维格那分布过渡.     

Electron excitation from ground state to first excited state:Bohmian mechanics method

The excitation process of electrons from the ground state to the first excited state via the resonant laser pulse is investigated by the Bohmian mechanics method. It is found that the Bohmian particles far away from the nucleus are easier to be excited and are excited firstly, while the Bohmian particles in the ground state is subject to a strong quantum force at a certain moment, being excited to the first excited state instantaneously. A detailed analysis for one of the trajectories is made, and finally we present the space and energy distribution of 2000 Bohmian particles at several typical instants and analyze their dynamical process at these moments.     

Crystallization of an electron gas

The ground state energy of an electron gas that is evaluated by the method of Padé approximants shows a singularity which may be associated with the formation of the Wigner lattice. The energy curve in the vicinity of this singularity is examined, and the pressure and the correlation energy are evaluated. Permanent address: Department of Physics, State University of New York at Buffalo, N.Y., U.S.A.     

Dynamic response functions of Hubbard model in Gutzwiller approximation

We calculate the two-point dynamic response functions of the Hubbard model at any filling from a slave-boson representation in the paramagnetic saddle point approximation. We use a spin-rotation invariant form of the representation due to Kotliar and Ruckenstein, for which the saddle point corresponds to Gutzwiller's variational approximation. In addition to the spin and charge susceptibilities, which have the familiar RPA form in the limit of small wavevectorq, the double and single-occupancy response functions are here calculated for the first time.Work partially performed at Department of Physics, University of Florida, Gainesville, FL 32611, USA     

Ground State Properties for Bose-Condensed Gas in Anisotropic Traps

Based on the energy functional and variational method, we present a new method to investigate the ground state properties for a weakly interacting Bose-condensed gas in an anisotropic harmonic trap at zero temperature. With this method we are able to find the analytic expression of the ground-state wavefunction and to explore the relevant quantities, such as energy, chemical potential, and the aspect ratio of the velocity distribution. These results agree well with previous ground state numerical solutions of the Gross-Pitaevskii equation given by Dalfovo et al. [Phys. Rev. A 53 （1996） 2477] This new method is simple compared to other methods used to solve numerically the Gross-Pitaevskii equation, and one can obtain analytic and reliable results.     

Stability of the ground state of a harmonic oscillator in a monochromatic wave

The stability of the ground state of a harmonic oscillator in a monochromatic wave is studied. This model describes, in particular, the dynamics of a cold ion in a linear ion trap, interacting with two laser fields with close frequencies. The stability of the "classical ground state"-the vicinity of the point (x=0,p=0)-is analyzed analytically and numerically. For the quantum case, a method for studying a stability of the quantum ground state is developed, based on the quasienergy representation. It is demonstrated that stability of the ground state may be substantially improved by increasing the resonance number, l, where l=Omega/omega+delta, Omega and omega are, respectively, the wave frequency and the oscillator frequency, l=1,2, em leader, mid R:deltamid R:<1; or by detuning the system from exact resonance, so that delta not equal 0. The influence of a large-amplitude wave (in the presence of chaos) on the stability of the ground state is analyzed for different parameters of the model in both the quantum and classical cases. (c) 2001 American Institute of Physics.     

Investigation of the Models of Magnetic Dendrimers by the Wang–Landau Method

Physics of the Solid State - The thermodynamic properties of the models of magnetic dendrimers were studied by the Monte Carlo method. The system state density is calculated; the ground state...     

Cumulant t-Expansion for Strongly Correlated Electrons on a Lattice

Journal of Experimental and Theoretical Physics - A systematic nonperturbative scheme for calculating the ground state energy is adapted for studying systems of strongly correlated electrons on a...     

Exact Perturbative Results for the Lieb–Liniger and Gaudin–Yang Models

Journal of Statistical Physics - We present a systematic procedure to extract the perturbative series for the ground state energy density in the Lieb–Liniger and Gaudin–Yang models,...     

Antiferromagnetism and correlation of electrons in a one-band Hubbard model

The effect of electron correlations on the antiferromagnetic ground state of the oneband Hubbard model is examined. The ground state is found analytically for a rectangular density of states. The region of ordered states is reduced as compared with the mean-field results due to formation of local moments and suppression of charge fluctuations with increasing Coulomb interaction between electrons. Local moments present in the paramagnetic phase have almost the same values as those existing in the antiferromagnetic one. For a half-filled band antiferromagnetism is not destroyed by correlation effects in the limit of weak interactions.On leave of absence from the Institute of Physics, Jagellonian University, Cracow, Poland     

Ground state projection of quantum spin systems in the valence-bond basis

A Monte Carlo method for quantum spin systems is formulated in the valence-bond basis. The nonorthogonality allows for an efficient importance-sampled projection of the ground state out of an arbitrary state. The method provides access to resonating valence-bond physics, enables a direct estimator for the singlet-triplet gap, and extends the class of models that can be studied without negative-sign problems. As a demonstration, the valence-bond distribution in the ground state of the 2D Heisenberg antiferromagnet is calculated. Generalizations of the method to fermion systems are also discussed.     

A new approximating method for Holstein model

A new approach-the method of coherent state orthogonal expansion is developed for one-dimensional Holstein model. In zeroth order approximation, the formula of ground state energy is deduced analytically and the solutions in strong- and weak-coupling limits are obtained correctly. When the trial wave-function of ground state is expanded to the second order, the obtained ground state energy agrees quite well with that calculated by numerical method in all coupling regimes. The present approach can be easily ...     

13N的一个可能的类晕的质子2p态

假设¹³N是单粒子的2p态的结构,用Glauber多重散射理论计算了1GeV的质子在¹³N上弹性散射的微分截面,研究了¹³N的类晕结构.与¹³C的情况不同,虽然目前还没有关于p-¹³N弹性散射微分截面的实验材料与我们的理论结果相比较,但是这个理论结果可以作为对未来的实验测量工作的一个指导,特别是对兰州近代物理研究所的晕核实验研究工作有参考和指导价值.参照先前我们对¹³C晕核结构的理论预言和进而的实验证实,本文的计算结果清楚地表明:¹³N可能存在着一个类晕的质子皮结构.因此,实验上测量p-¹³N弹性散射的微分截面就是当前需要马上进行的一个实验研究工作.     

Nontrivial Ground State Degeneracy of the Spin–Pseudospin Model of a Two-Dimensional Magnet Near the Frustration Point

Physics of the Solid State - The classical Monte Carlo method is used to study the properties of the ground state and phase transitions of the spin–pseudospin model, which describes a...     

Studying Thermodynamic Properties of the Ising Model on a Body-Centered Cubic Lattice with Competing Exchange Interactions

Physics of the Solid State - Using the Monte Carlo method, magnetic structures of the ground state and thermodynamic properties of the antiferromagnetic Ising model on a body-centered cubic lattice...     

Bounded Entanglement Entropy in the Quantum Ising Model

Journal of Statistical Physics - A rigorous proof is presented of the boundedness of the entanglement entropy of a block of spins for the ground state of the one-dimensional quantum Ising model...     

Remote sensing of atmospheric ozone at millimeter waves

We present new results of remote sensing of the vertical distribution of ozone at millimeter waves using the FIAN (P.N. Lebedev Institute of Physics, Russian Academy of Sciences) high-sensitivity spectroradiometer which includes a new 96-channel spectrum analyzer AS-96 with improved characteristics. The ozone radiation spectrum is recorded at a frequency of 142.2 GHz. Vertical profile of ozone is retrieved using an improved algorithm based on Tikhonov’s method and statistical regularization technique. Specific features of the altitude-temporal distribution of ozone, which reflects ozonospheric processes above mid-latitudes are considered. Variations in the vertical distribution of ozone during major stratospheric warming in January 2009 are shown. It was concluded that the creation of a national ground-based network for ozone monitoring at millimeter waves in Russia is a must.     

Aharonov-Bohm effect in spherical billiard

Using Gutzwiller's periodic orbit theory, we study the quantum level density of a spherical billiard in the presence of a magnetic flux line added at its center, especially discuss the influence of the magnetic flux strength on the quantum level density. The Fourier transformed quantum level density of this system has allowed direct comparison between peaks in the level density and the length of the periodic orbits. For particular magnetic flux strength, the amplitude of the peaks in the level density decreased and some of the peaks disappeared. This result suggests that Aharonov-Bohm effect manifests itself through the cancellation of periodic orbits. This phenomenon will provide a new experimental testing ground for exploring Aharonov-Bohm effect.     

On the ground state of ferromagnetic Hamiltonians

It is generally believed that the ground state of the ferromagnetic Heisenberg-Dirac-Van Vleck Hamiltonians acting ons=1/2 spins of a lattice withN sites has the maximum possible value of the total spinS=N/2 and isN+1 times degenerate. We present a rigorous proof of this statement, independent of the lattice dimension and topology. A member of the Doppler Institute of Mathematical Physics, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Prague.