共查询到20条相似文献,搜索用时 187 毫秒
1.
XIE Wen-Fang 《理论物理通讯》2007,48(2):331-334
The helium atom confined by a spherical parabolic potential well is studied employing the adiabatic hyperspherical approach method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the energies of a spherical parabolic potential well are in good agreement with those of an impenetrable spherical box for the larger confined potential radius. We find also that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other. We find that the energy difference between states in a two-dimensional parabolic potential is also obviously larger than the corresponding levels for a spherical parabolic potential. 相似文献
2.
Calculation of Energies of the Ground and Low Excited States of a Confined Helium Atom in a Spherical Parabolic Well
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Making use of the adiabatic hyperspherical approach, we report a calculation for the energy spectrum of the ground and low-excited states of the confined helium atom in a spherical parabolic well. We find that the energies of a spherical parabolic well are in good agreement with those of an impenetrable spherical box for the larger confined potential radius. However, the energy values of a spherical parabolic well are much lower than those of an impenetrable spherical box for small values of re. We also find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. 相似文献
3.
XIE Wen-Fang 《理论物理通讯》2008,49(5):1287-1290
The helium atom confined by a non-impenetrable spherical box, i.e., a spherical Gaussian potential well which possesses finite height and range, is studied employing the exact diagonalization method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other: in general, the energies of the states decrease and the energy intervals between states increase with the reduction of the space dimensions. 相似文献
4.
XIE Wen-Fang 《理论物理通讯》2007,47(6):1111-1113
The ground and three low-excited states of the hydrogen negative ion confined by a spherical harmonic oscillator potential are studied employing the adiabatic hyperspherical approach method. Total energies are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. 相似文献
5.
XIE Wen-Fang 《理论物理通讯》2007,47(3):547-549
The ground and three low-excited states of the positronium negative ion confined by a spherical harmonic oscillator potential are studied employing the adiabatic hyperspherical approach method. Total energies are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different Iow-excited states and the inversion of the energy values. 相似文献
6.
In this paper, we studied the effects of an electric field on a hydrogenic impurity confined in a spherical parabolic quantum dot using nondegenerate and degenerate perturbation methods. The binding energies of the ground and three low-excited states are calculated as a function of the confinement strength and as a function of the intensity of an applied electric field. Moreover, we computed the oscillator strength and the second-order nonlinear optical rectification coefficient based on the computed energies and wave functions. The results show that the electric and optical properties of hydrogenic impurity states are strongly affected by the confinement strength and the applied electric field. 相似文献
7.
The energy levels and binding energies of a hydrogenic impurity in GaAs spherical quantum dots with radius R are calculated by the finite difference method. The system is assumed to have an infinite confining potential well with radius R, which can be viewed as a hard wall boundary condition. The parabolicity of the conduction band profile for GaAs material can be viewed as a parabolic potential well. The energy levels and binding energies are depended dramatically on the radius of the quantum dot and the parabolic potential well. The results show that parabolic potential can remarkably alter the energy level ordering and binding energy level ordering of hydrogenic impurity states for the quantum dot with a smaller radius R. 相似文献
8.
XIE Wen-Fang 《理论物理通讯》2008,49(2):507-510
The properties of the low-lying states of a negative donor center trapped by
a spherical quantum dot, which is subjected to a parabolic potential
confinement, are investigated in the absence of magnetic field. The
calculations have been performed by means of the exact diagonalization of
the Hamiltonian matrix within the effective-mass approximation. We find that there is only one bound state the D- center in a spherical parabolic quantum dot in the absence of magnetic field. The binding energy of the ground state is obtained as a function of the dot size. Moreover, the critical confined potential radius value at which the negative donor center changes from unbound to bound is obtained. 相似文献
9.
A. Csordás J. Cserti A. Pályi U. Zülicke 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):189-200
We study the energy levels of non-interacting electrons confined to move in two-dimensional billiard regions and having a
spin-dependent dynamics due to a finite Rashba spin splitting.
The free space Green's function for such Rashba
billiards is constructed analytically and used to find the area and perimeter contributions to the density of states, as well
as the corresponding smooth counting function. We show that, in contrast to systems with spin-rotational invariance, Rashba
billiards always possess a negative energy spectrum. A semi-classical analysis is presented to interpret the singular behavior
of the density of states at certain negative energies
for circular Rashba billiards. Our detailed analysis of the spin structure of circular Rashba billiards reveals a finite out-of-plane
spin projection for electron eigenstates. 相似文献
10.
施加电场的半抛物量子阱中束缚态的能级结构 总被引:3,自引:0,他引:3
采用位移谐振子与数值求解相结合的方法,研究和讨论了施加电场的半抛物量子阱中束缚态的能级结构,得到了体系的本征能量与本征函数的表达式.数值结果显示,随着电场强度的增大,束缚态的能量几乎线性地下降,电场对半抛物束缚势频率较低的系统以及系统的高能级的影响较大,相邻能级间隔也随着电场强度的增大而减小,这与施加电场的抛物量子阱中的情况明显不同. 相似文献
11.
XIE Wen-Fang 《理论物理通讯》2005,44(7)
Making use of the adiabatic hyperspherical approach, we report a calculation for the energy spectrum of the ground and low-excited states of a two-dimensional helium in a magnetic field. The results show that the ground and low-excited states of helium in low-dimensional space are more stable than those in three-dimensional space and there may exist more bound states. 相似文献
12.
We explore the non-commutative (NC) effects on the energy spectrum of a two-dimensional hydrogen atom. We consider a confined particle in a central potential and study the modified energy states of the hydrogen atom in both coordinates and momenta of non-commutativity spaces. By considering the Rashba interaction, we observe that the degeneracy of states can also be removed due to the spin of the particle in the presence of NC space. We obtain the upper bounds for both coordinates and momenta versions of NC parameters by the splitting of the energy levels in the hydrogen atom with Rashba coupling. Finally, we find a connection between the NC parameters and Lorentz violation parameters with the Rashba interaction. 相似文献
13.
We present a theoretical study of the energy levels with two-dimensional ring confining potential in the presence of the Rashba spin-orbit interaction. The features of some low-lying states in various strengths of the Rashba spin-orbit interaction are investigated. The Rashba spin-orbit splitting can a/so be influenced by the width of the potential barrier. The computed results show that the spin-polarized electronic states can be more easily achieved in a weakly confined dot when the confinement strength for the Rashba spin-orbit interaction is larger than a critical value. 相似文献
14.
XIE Wen-Fang 《理论物理通讯》2004,42(7)
Two-electron states of a three-dimensional spherical GaAs quantum dot (QD) with a Gaussian confining potential confinement are studied. Calculations are made by using the method of few-body physics within the effectivemass approximation. We have calculated the energy levels of single and triplet states as functions of the range and depth of the confining potential well in the spherical QDs. The same calculations performed with the parabolic approximation of the Gaussian potential lead to the results, which are qualitatively and quantitatively different. 相似文献
15.
Making use of the adiabatic hyperspherical approach, we report a calculation for the energy spectrum of the ground and low-excited states of a two-dimensional hydrogen negative ion H^{-} in a magnetic field. The results show that the ground and low-excited states of H^{-} in low-dimensional space are more stable than those in three-dimensional space and there may exist more bound states. 相似文献
16.
XIE Wen-Fang 《理论物理通讯》2004,41(1):127-130
The energy spectra of the ground state for an exciton
(X) trapped by a neutral acceptor
(A0) in a quantum dot with a
parabolic confinement
have been calculated as a function of the electron-to-hole mass ratio σ
by using the hyperspherical coordinates.
We find that the (A0,X) complex confined in a
quantum dot has in general a larger binding energy
than those in a two-dimensional quantum well and a three-dimensional bulk
semiconductor, and the binding energy decreases with the increase of the
electron-to-hole mass ratio. 相似文献
17.
W. Karboul-Trojet Y. Roussigné D. Faurie S. M. Chérif 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(10):1-7
The influence of an external electric field on the binding energies of the ground state and excited states with the third-harmonic-generation (THG) coefficient for spherical quantum dot (QD) with parabolic confinement is investigated theoretically. The energy levels and wave functions of electronic states in the QDs are calculated using by variational method within the effective-mass approximation. The numerical results demonstrate that the THG coefficient very sensitively depends on the magnitude of the electric field and the radius of the QDs. In addition, the THG coefficient also depends on the relaxation rate of the spherical QD with parabolic confinement and the position of impurity. 相似文献
18.
XIE Wen-Fang 《理论物理通讯》2008,49(3):763-766
In this paper, we study four electrons confined in a
parabolic quantum dot in the absence of magnetic field, by the exact
diagonalization method. The ground-state electronic structures and orbital
and spin angular momenta transitions as a function of the confined
strength are investigated. We find that the confinement may cause
accidental degeneracies between levels with different low-lying states and
the inversion of the energy values. The present results are useful to
understand the optical properties and internal electron-electron
correlations of quantum dot materials. 相似文献
19.
In analogy with the definition of resonant or quasi-bound states used in three-dimensional quantal scattering, we define the
quasi-bound states that occur in one-dimensional transmission generated by twin symmetric potential barriers and evaluate
their energies and widths using two typical examples: (i) twin rectangular barrier and (ii) twin Gaussian-type barrier. The
energies at which reflectionless transmission occurs correspond to these states and the widths of the transmission peaks are
also the same as those of quasi-bound states. We compare the behaviour of the magnitude of wave functions of quasi-bound states
with those for bound states and with the above-barrier state wave function. We deduce a Breit-Wigner-type resonance formula
which neatly describes the variation of transmission coefficient as a function of energy at below-barrier energies. Similar
formula with additional empirical term explains approximately the peaks of transmission coefficients at above-barrier energies
as well. Further, we study the variation of tunnelling time as a function of energy and compare the same with transmission,
reflection time and Breit-Wigner delay time around a quasi-bound state energy. We also find that tunnelling time is of the
same order of magnitude as lifetime of the quasi-bound state, but somewhat larger. 相似文献
20.
In this Letter, a different method was given for calculating the energies of the magnetobipolarons confined in a parabolic QD (quantum dot). We introduced single-mode squeezed states transformation, which are based on the Lee-Low-Pines and Huybrechts (LLP-H) canonical transformations. This method can provide results not only for the ground state energy but also for the excited states energies. Moreover, it can be applied to the entire range of the electron-phonon coupling strength. Comparing with the results of the LLP-H transformations, we have obtained more accurate results for the ground state energy, excited states energies and binding energy of the bipolarons. It shows that the magnetic field and the quantum dot can facilitate the formation of the bipolarons when η is smaller than some value. 相似文献