共查询到20条相似文献,搜索用时 203 毫秒
1.
利用B-splines特性构建量子点中激子的波函数,计算PbS量子点中激子的基态能量Eg的量子尺寸效应,并将计算结果与实验结果及其他理论计算结果进行比较;利用B-splines技术计算的激子的基态能量在整个区域与实验完全符合,同时计算了有效质量和势垒高度对基态能量Eg的量子尺寸效应的影响. 相似文献
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利用二维有限差分方法,计算了含有H_2~+杂质的方形量子点的基态能和杂质束缚能。讨论了磁场和杂质位置对不同尺寸的量子点中电子基态能量和束缚能的影响,得出了方形量子点系统的量子尺寸效应。 相似文献
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声子之间的相互作用对量子线中极化子性质的影响 总被引:3,自引:3,他引:0
研究了量子线中弱耦合极化子的性质。采用线性组合算符和微扰法导出量子线中弱耦合极化子的基态能量。在计及电子在反冲效应中发射和吸收不同波矢的声子之间的相互作用时,讨论了量子线的受限强度﹑电子-LO声子耦合强度和声子之间相互作用对量子线中弱耦合极化子的基态能量的影响。数值计算结果表明:量子线中弱耦合极化子的基态能量 随量子线的受限强度 的增大而增大, 表现出了量子线的量子尺寸效应。 相似文献
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施加电场的半抛物量子阱中的电光效应 总被引:1,自引:0,他引:1
利用量子力学中的紧致密度矩阵方法,研究了施加电场的半抛物量子阱中的电光效应。通过位移谐振子变换,得到了系统中的电子态的精确解。对典型的GaAs材料进行数值计算的结果表明,随着电场强度的增加,电光效应系数几乎线性随之增加;但是随着半抛物量子阱受限势频率的增加,电光效应系数单调地减小;而且在同样的电场强度及抛物束缚势频率作用下,半抛物量子阱模型中的电光效应系数比抛物量子阱模型中的值大两个数量级,这是由于我们所选模型本身的非对称性以及电场进一步使这种非对称性增强的缘故。 相似文献
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Keith Benedict 《Contemporary Physics》2013,54(4):365-366
The concept of the superdeformed shape is first introduced classically as the most stable configuration of a rapidly rotating deformable body and is then applied to nuclei. The shape of nuclei are determined by a competition between the collective energy of the core, to which classical considerations apply quite well, and the quantal energies of the valence nucleons, which may be evaluated by the Nilsson model. The result of this competition is that slowly rotating nuclei can be either oblate or prolate but rapidly rotating nuclei can have a superdeformed prolate shape, with a 2:1 ratio of axes particularly favoured. The evidence for superdeformation in nuclei is described under four headings. Firstly, some light nuclei are superdeformed in their ground state or in an excited state. Secondly, some nuclei pass through a well defined superdeformed shape on the way to fission. Thirdly, studies of the excitation functions of elastic and inelastic scattering of identical heavy ions provide evidence of a nuclear molecule in a superdeformed shape. Finally, recent analyses of gamma rays from nuclei formed in a very high spin state by a heavy ion collision provide conclusive evidence for superdeformation. 相似文献
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The phenomenon of the disappearance of the shell effects on the thermodynamic properties of nuclei with increasing excitation
energy has been examined quantitatively on the basis of numerical calculations based on realistic shell model single particle
level schemes. It is shown that shell effects disappear at moderate excitation energies and above these excitation energies,
the thermodynamic behaviour of the nucleus is identical to that of the equivalent liquid drop model nucleus. Implications
of the above feature in the interpretation of some aspects of fission of excited nuclei such as mass-asymmetry and angular
anisotropy are examined. The relationship of the phenomenon of washing out of shell effects at high excitation energies with
the temperature smearing method of determining ground state shell correction energies is also outlined. 相似文献
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M.B. Smith R. Chapman J.F.C. Cocks O. Dorvaux K. Helariutta P.M. Jones R. Julin S. Juutinen H. Kankaanpää H. Kettunen P. Kuusiniemi Y. Le Coz M. Leino D.J. Middleton M. Muikku P. Nieminen P. Rahkila A. Savelius K.-M. Spohr 《The European Physical Journal A - Hadrons and Nuclei》1999,5(1):43-47
Excited states in the Z= 85 nucleus 197At have been identified for the first time using the recoil-decay-tagging (RDT) technique. The excitation energy of these
states is found to be consistent with the systematics of neutron-deficient astatine nuclei and with theoretical calculations
indicating that the nucleus may be deformed in its ground state.
Received: 8 January 1999 相似文献
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Microscopic optical potential calculations in the Hartree-Fock (HF) approximation with Extended Skyrme forces are investigated. The HF equation is derived from the variation principle and the potential formula of spherical nuclei is obtained by two different ways. Then the calculations for symmetric nuclei 16O, 40Ca and asymmetric nucleus 90Zr with eight sets of Skyrme force parameters are presented. Our results show that the potential from and variating tendency with incident energy are reasonable and there apparently appears a "wine-bottle-bottom" shape in the intermediate energy region. Furthermore, our calculations reflect shell effects clearly. 相似文献
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Bertsch GF Girod M Hilaire S Delaroche JP Goutte H Péru S 《Physical review letters》2007,99(3):032502
We report the first comprehensive calculations of 2(+) excitations with a microscopic theory applicable to over 90% of the known nuclei. The theory uses a quantal collective Hamiltonian in five dimensions. The only parameters in theory are those of the finite-range, density-dependent Gogny D1S interaction. The following properties of the lowest 2(+) excitations are calculated: excitation energy, reduced transition probability, and spectroscopic quadrupole moment. We find that the theory is very reliable to classify the nuclei by shape. For deformed nuclei, average excitation energies and transition quadrupole moments are within 5% of the experimental values, and the dispersion about the averages are roughly 20% and 10%, respectively. Including all nuclei in the performance evaluation, the average transition quadrupole moment is 11% too high and the average energy is 13% too high. 相似文献
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Sarazin F Savajols H Mittig W Nowacki F Orr NA Ren Z Roussel-Chomaz P Auger G Baiborodin D Belozyorov AV Borcea C Caurier E Dlouhy Z Gillibert A Lalleman AS Lewitowicz M Lukyanov SM de Oliveira F Penionzhkevich YE Ridikas D Sakurai H Tarasov O de Vismes A 《Physical review letters》2000,84(22):5062-5065
The masses of 31 neutron-rich nuclei in the range A = 29-47 have been measured. The precision of 19 masses has been significantly improved and 12 masses were measured for the first time. The neutron-rich Cl, S, and P isotopes are seen to exhibit a change in shell structure around N = 28. Comparison with shell model and relativistic mean field calculations demonstrate that the observed effects arise from deformed prolate ground state configurations associated with shape coexistence. Evidence for shape coexistence is provided by the observation of an isomer in 43S. 相似文献
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We explain by quantal density functional theory the physics of mapping from any bound nondegenerate excited state of Schr?dinger theory to an S system of noninteracting fermions with equivalent density and energy. The S system may be in a ground or excited state. In either case, the highest occupied eigenvalue is the negative of the ionization potential. We demonstrate this physics with examples. The theory further provides a new framework for calculations of atomic excited states including multiplet structure. 相似文献
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V. L. Litnevsky G. I. Kosenko F. A. Ivanyuk V. V. Pashkevich 《Physics of Atomic Nuclei》2011,74(7):1001-1009
The motion of two nuclei toward each other in fusion-fission reactions is considered. The state of the system of interacting
nuclei is specified in terms of three collective coordinates (parameters). These are the distance between the centers of mass
of the nuclei and the deformation parameter for each of them (the nose-to-nose orientation of the nuclei is assumed). The
evolution of collective degrees of freedom of the system is described by Langevin equations. The energies of the Coulomb and
nuclear (Gross-Kalinovsky potential) interactions of nuclei are taken into account in the potential energy of the system along
with the deformation energy of each nucleus with allowance for shell effects. The motion of nuclei toward each other are calculated
for two reaction types: reactions involving nuclei that are deformed (42100Mo + 42100Mo → 84200Po) and those that are spherical (82208Pb + 818O → 90226Th) in the ground state. It is shown that the shell structure of interacting nuclei affects not only the fusion process as
a whole (fusionbarrier height and initial-reaction-energy dependence of the probability that the nuclei involved touch each
other) but also the processes occurring in each nucleus individually (shape of the nuclei and their excitation energies at
the point of touching). 相似文献
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Results of number projected quasiparticle calculations for Sn isotopes in large and in small model spaces are compared when the force strengths and single-particle energies are determined consistently within each model space. When extending the model space, one observes that the model parameters extracted from the odd nuclei become more satisfactory. For even nuclei the collective states are not lowered in energy although electromagnetic transition rates increase considerably. Spectroscopic factors for one-nucleon transfer reactions change noticeably only for shells close to the Fermi level. Two-nucleon transfer cross-sections are strongly increased for ground state to ground state transitions only. We criticize a usual approximation formula for theL=0 two-nucleon transfer cross-section. 相似文献