共查询到20条相似文献,搜索用时 15 毫秒
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A microscopic cluster model with a fully correlated Gaussian basis is developed. In the model, the stochastic variational method is used in order to calculate the ground-energy and the mean-square radius conveniently. Based on this model, the ground-energy level and radius of the neutron halo nucleus, <'6>He, are calculated as a α+n+n three-cluster model. The results are in good agreement with the experimental data. 相似文献
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Ground state energy of He isoelectronic sequence treated variationally via Hylleraas-like wavefunction 下载免费PDF全文
In this study, the energy for the ground state of helium and a few helium-like ions (Z=1-6) is computed variationally by using a Hylleraas-like wavefunction. A four-parameters wavefunction, satisfying boundary conditions for coalescence points, is combined with a Hylleraas-like basis set which explicitly incorporates r12 interelectronic distance. The main contribution of this work is the introduction of modified correlation terms leading to the definition of integral transforms which provide the calculation of expectation value of energy to be done analytically over single-particle coordinates instead of Hylleraas coordinates. 相似文献
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Edit Mátyus 《Molecular physics》2013,111(5):590-609
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A consistent theoretical analysis of elastic α 6He scattering is performed with allowance for the correction associated with the exchange of a dineutron cluster. It is shown that the inclusion of the exchange mechanism, along with that of potential scattering, makes it possible to reproduce the measured cross section over the entire range of the 6He scattering angle. Concurrently, one can also obtain information about the spatial distribution of the dineutron cluster and the α particle in the ground state of the 6He nucleus. 相似文献
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Mahmood Mian 《Pramana》1993,41(2):145-149
The binding energy of the double hypernucleus
ΛΛ
6
is calculated in α + 2Λ cluster model using the method of translation invariant basis TIMO. As regards the required interaction
potentials we use a density dependent effective ΛN force and a gaussian form for ΛΛ potential. With these interactions a very reasonable value ofB
ΛΛ is obtained if the oscillator states up to the excitation quantum numberN=12 are taken into account in the expansion of wavefunction of the hypernucleus. This value ofN is much smaller than that obtained in an earlier study. This lowering inN value is attributed to a much better choice of ΛN potential used in the present study. 相似文献
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Heinz Stöwe Hans H. Hackenbroich Hannes Hutzelmeyer 《Zeitschrift für Physik A Hadrons and Nuclei》1971,247(2):95-106
A soft core central potential is used to calculate independently6Li ground state and excited state wave functions in the refined cluster model. Charge density, elastic formfactor and transition formfactor to the 3+ state are derived and agree reasonably well with experiment. 相似文献
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Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method.To be specific,precise energy eigenvalues of bound 1sns(~1S~e)(n=1-6)states and the resonance parameters i.e.positions and widths of~lS~e states due to 2sns(n=2-5)and 2pnp(n=2-5)configurations of confined helium below N=2 ionization threshold of He~+have been estimated.The two-parameter(Depth and Width)finite oscillator potential is used to represent the confining potential due to the quantum dot.It has been explicitly demonstrated that the electronic structural properties become sensitive functions of the dot size.It is observed from the calculations of ionization potential that the stability of an impurity ion within a quantum dot may be manipulated by varying the confinement parameters.A possibility of controlling the autoionization lifetime of doubly excited states of two-electron ions by tuning the width of the quantum cavity is also discussed here. 相似文献
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张高龙 叶沿林 江栋兴 郑涛 李智焕 李湘庆 吴翠娥 陈志强 胡青元 庞丹阳 王佳 A.Ozawa Y.Yamaguchi R.Kanungo D.Fang I.Tanihata 《中国物理 C》2005,29(10):940-943
在25MeV/u 6He轰击9Be靶的反应中,用探测器望远镜测得氚碎片,得到了5个角度的能谱,经过仔细的分析取得了高能直接破碎成分的角分布.利用Serber模型进行了破碎反应的理论计算,证实了实验中高能成分的t来自于6He的直接破碎反应.利用Fermi破碎模型计算了6He中各破碎反应道基于相空间的百分比产额,进而估算出6He初态中t+t结构的概率约占1/3, 而4He核心加价中子的组态约占2/3. 相似文献
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The properties of the 6He nucleus were investigated in a three-particle approximation (a alpha-particle cluster plus two neutrons) on the basis of the variational approach by using a Gaussian basis. For nn and nα interactions, potentials that make it possible to describe S-wave phase shifts for elastic scattering and, simultaneously, to reproduce faithfully the energy and the size of the 6He nucleus were proposed. Characteristic structural features of this nucleus that are manifested in the density distributions, elastic form factor, pair correlation functions, and momentum distributions of particles constituting the 6He nucleus in the three-particle model were revealed. 相似文献
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A. Careta F. Sagués L. Ramirez-Piscina J. M. Sancho 《Journal of statistical physics》1993,71(1-2):235-242
Analytical results are derived for the effective dispersion of a passive scalar in a stochastic velocity field evolving in a fast time scale. These results are favorably compared with direct computer simulation of stochastic differential equations containing multiplicative space-time correlated noise. 相似文献
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A. G. Schlijper 《Journal of statistical physics》1988,50(3-4):689-714
In cluster approximations for lattice systems the thermodynamic behavior of the infinite system is inferred from that of a relatively small, finite subsystem (cluster), approximations being made for the influence of the surrounding system. In this context we study, for translation-invariant classical lattice systems, the conditions under which a state for a cluster admits an extension to a global translation-invariant state. This extension problem is related to undecidable tiling problems. The implication is that restrictions of global translation-invariant states cannot be characterized purely locally in general. This means that there is an unavoidable element of uncertainty in the application of a cluster approximation. 相似文献
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We have examined the validity of the time-dependent variational approximation (TDVA) to the Gaussian wavepacket method (GWM) for quantum double-well (DW) systems, by using the quasi-exact spectral method (SM). Comparisons between results of wavefunctions, averages of position and momentum, the auto-correlation function, and an uncertainty product calculated by SM and TDVA have been made. It has been shown that a given initial Gaussian wavepacket in SM is quickly deformed at t>0 where a wavepacket cannot be expressed by a single Gaussian, and that assumptions on averages of higher-order fluctuations in TDVA are not justified. These results cast some doubt on an application of TDVA to DW systems. Gaussian wavepacket dynamics in anharmonic potential systems is studied also. 相似文献
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Quantum computing for the Lipkin model with unitary coupled cluster and structure learning ansatz 下载免费PDF全文
We report a benchmark calculation for the Lipkin model in nuclear physics with a variational quantum eigensolver in quantum computing. Special attention is paid to the unitary coupled cluster (UCC) ansatz and structure learning (SL) ansatz for the trial wave function. Calculations with both the UCC and SL ansatz can reproduce the ground-state energy well; however, it is found that the calculation with the SL ansatz performs better than that with the UCC ansatz, and the SL ansatz has even fewer quantum gates than the UCC ansatz. 相似文献
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众所周知, 风场分解与重构最有效的方法就是引入速度势和流函数, 其一般通过求解两个Poisson 方程得到. 由于速度势和流函数在边界上的耦合性质,有限区域风场分解是不唯一的, 这对风场分解带来了很大困难. 本文采用变分伴随结合正则化方法来克服风场分解的不唯一性, 其核心是把速度势和流函数的边值作为控制变量来反演. 目标泛函由两部分组成, 一是衡量重构风场误差大小的观测项; 二是保证风场分解问题适定的正则化项, 其目的在于寻求具有气象意义的稳定正则化解. 数值试验结果表明, 在正确选取正则化参数后, 利用变分伴随结合正则化方法进行有限区域风场分解与重构是有效可行的. 相似文献
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T. Morita 《Journal of statistical physics》1984,34(1-2):319-328
A redundancy is noted in the set of Lagrange multipliers—effective fields and effective interactions—used in the expressions of the reduced density matrices given by Morita(4) in some problems with less symmetry(6). The expressions of the reduced density matrices without this redundancy are given. An argument showing that a certain expression of the free energy in terms of the Lagrange multipliers is stationary with respect to the variations of these is presented. 相似文献