Based on the Huybrechts' linear-combination operator,effects of thermal lattice vibration on the effective potential of weak-coupling bipolaron in semiconductor quantum dots are studied by using the LLP variationa...Based on the Huybrechts' linear-combination operator,effects of thermal lattice vibration on the effective potential of weak-coupling bipolaron in semiconductor quantum dots are studied by using the LLP variational method and quantum statistical theory.The results show that the absolute value of the induced potential of the bipolaron increases with increasing the electron-phonon coupling strength,but decreases with increasing the temperature and the distance of electrons,respectively;the absolute value of the effective potential increases with increasing the radius of the quantum dot,electron-phonon coupling strength and the distance of electrons,respectively,but decreases with increasing the temperature;the temperature and electron-phonon interaction have the important influence on the formation and state properties of the bipolaron:the bipolarons in the bound state are closer and more stable when the electron-phonon coupling strength is larger or the temperature is lower;the confinement potential and coulomb repulsive potential between electrons are unfavorable to the formation of bipolarons in the bound state.展开更多
The motion of a bipolaron in the quantum well wire(QWW) has been investigated based on weakly or intermediately coupling with the surface optical phonon.This kind of system,in some sense,may represent the behaviour ...The motion of a bipolaron in the quantum well wire(QWW) has been investigated based on weakly or intermediately coupling with the surface optical phonon.This kind of system,in some sense,may represent the behaviour of bipolaron in high temperature ceramic superconductors.The Hamiltonian of the system is first transformed by double unitary transformation,so that some of the relevant quantities,such as the phonon induced potential energies V e so and U e so( z) ,can be calculated.The results of our calculation indicate that both of the phonon induced potential energies are strengthened as the radius ρ o of the QWW becomes thinner.However,this is valid merely for ρ o to be greater than a specific value that corresponds to the minimum of the energy.The total effective potential energy V eff ( z ) for the bipolaron in the QWW is also evaluated.The result of this wholy effective potential energy indicates that there is an equilibrium position for the two electrons which form the bipolaron.This position depends also on the radius of the QWW.The justification for our theoretical calculations awaits experimental results for future development in the low dimensional structure of superconductivity.展开更多
The properties of large bipolarons in two and three dimensions are investigated by averaging over therelative wavefunction of the two electrons and using the Lee-Low-Pines-Huybrechts variational method.The ground-stat...The properties of large bipolarons in two and three dimensions are investigated by averaging over therelative wavefunction of the two electrons and using the Lee-Low-Pines-Huybrechts variational method.The ground-state(GS)and excited-state energies of the Frhlich bipolaron for the whole range of electron-phonon coupling constantscan be obtained.The energies of the first relaxed excited state(RES)and Franck-Condon(FC)excited state of thebipolaron are also calculated.It is found that the first RES energy is lower than the FC state energy.The comparisonof our GS and RES energies with those in literature is also given.展开更多
The authors used Landau-Pekar variational method to investigate a strong-coupling singlet optical bipolaron in different configuration of quantum confinement. Numerical and analytical results showed that when configur...The authors used Landau-Pekar variational method to investigate a strong-coupling singlet optical bipolaron in different configuration of quantum confinement. Numerical and analytical results showed that when configuration changes from quantum dot and wire to well, confinement shows different effect on the formation of a bipolaron. In contrast to a bipolaron in a quantum dot or wire, the binding energy of a bipolaron in a quantum well increases with increasing con-finement, indicating that confinement favors bipolaron formation in a quantum well.展开更多
Based on the variational method of Pekar type, we study the energies and the wave-functions of the ground and the first-excited states of magneto-bipolaron, which is strongly coupled to the LO phonon in a parabolic po...Based on the variational method of Pekar type, we study the energies and the wave-functions of the ground and the first-excited states of magneto-bipolaron, which is strongly coupled to the LO phonon in a parabolic potential quantum dot under an applied magnetic field, thus built up a quantum dot magneto-bipolaron qubit. The results show that the oscillation period of the probability density of the two electrons in the qubit decreases with increasing electron–phonon coupling strength α, resonant frequency of the magnetic field ωc, confinement strength of the quantum dot ω0, and dielectric constant ratio of the medium η; the probability density of the two electrons in the qubit oscillates periodically with increasing time t, angular coordinate φ2, and dielectric constant ratio of the medium η; the probability of electron appearing near the center of the quantum dot is larger, and the probability of electron appearing away from the center of the quantum dot is much smaller.展开更多
The electronic properties of ground state and charged excited states of nondegenerate polydiacetylene were investigated by means of a tight-binding model. The parameters of the model were obtained by comparison of the...The electronic properties of ground state and charged excited states of nondegenerate polydiacetylene were investigated by means of a tight-binding model. The parameters of the model were obtained by comparison of the experimental and other theoretical results. It was found that there is a stable dimerized structure of polydiacetylene in ground state and the doping induces the nonlinear excitations, such as polarons and bipolarons. In order to compare the stability of polaron and bipolaron, the creation energy and binding energy were separately defined. By neglecting the electron-electron Coulomb interaction, a bipolaron is more stable than two independent polarons.展开更多
采用半经验Austin Model 1(AM1)方法,计算了齐分子吡咯聚合物(PPy)的中性态和带电态的几何结构性质.与中性态相比,带电态下其分子结构表现在C-C键长发生显著改变,单电荷掺杂导致极化子元激发;当掺杂的双电荷随机放置时,出现了两种情况:...采用半经验Austin Model 1(AM1)方法,计算了齐分子吡咯聚合物(PPy)的中性态和带电态的几何结构性质.与中性态相比,带电态下其分子结构表现在C-C键长发生显著改变,单电荷掺杂导致极化子元激发;当掺杂的双电荷随机放置时,出现了两种情况:一种情况下产生双极化子,另一种情况下会产生两个分立的极化子.通过控制链的长度,可实现极化子与双极化子之间的相变,从而揭示出在有机半导体材料中实现自旋极化输运的可能性.展开更多
基金Supported by the Items of Institution of Higher Education Scientific Research of Inner Mongolia under Grant No. NJ101116
文摘Based on the Huybrechts' linear-combination operator,effects of thermal lattice vibration on the effective potential of weak-coupling bipolaron in semiconductor quantum dots are studied by using the LLP variational method and quantum statistical theory.The results show that the absolute value of the induced potential of the bipolaron increases with increasing the electron-phonon coupling strength,but decreases with increasing the temperature and the distance of electrons,respectively;the absolute value of the effective potential increases with increasing the radius of the quantum dot,electron-phonon coupling strength and the distance of electrons,respectively,but decreases with increasing the temperature;the temperature and electron-phonon interaction have the important influence on the formation and state properties of the bipolaron:the bipolarons in the bound state are closer and more stable when the electron-phonon coupling strength is larger or the temperature is lower;the confinement potential and coulomb repulsive potential between electrons are unfavorable to the formation of bipolarons in the bound state.
文摘The motion of a bipolaron in the quantum well wire(QWW) has been investigated based on weakly or intermediately coupling with the surface optical phonon.This kind of system,in some sense,may represent the behaviour of bipolaron in high temperature ceramic superconductors.The Hamiltonian of the system is first transformed by double unitary transformation,so that some of the relevant quantities,such as the phonon induced potential energies V e so and U e so( z) ,can be calculated.The results of our calculation indicate that both of the phonon induced potential energies are strengthened as the radius ρ o of the QWW becomes thinner.However,this is valid merely for ρ o to be greater than a specific value that corresponds to the minimum of the energy.The total effective potential energy V eff ( z ) for the bipolaron in the QWW is also evaluated.The result of this wholy effective potential energy indicates that there is an equilibrium position for the two electrons which form the bipolaron.This position depends also on the radius of the QWW.The justification for our theoretical calculations awaits experimental results for future development in the low dimensional structure of superconductivity.
基金the Natural Science Foundation of the Education Bureau of Zhejiang Province under Grant No.200601309partially by National Natural Science Foundation of China under Grant No.10274067
文摘The properties of large bipolarons in two and three dimensions are investigated by averaging over therelative wavefunction of the two electrons and using the Lee-Low-Pines-Huybrechts variational method.The ground-state(GS)and excited-state energies of the Frhlich bipolaron for the whole range of electron-phonon coupling constantscan be obtained.The energies of the first relaxed excited state(RES)and Franck-Condon(FC)excited state of thebipolaron are also calculated.It is found that the first RES energy is lower than the FC state energy.The comparisonof our GS and RES energies with those in literature is also given.
文摘The authors used Landau-Pekar variational method to investigate a strong-coupling singlet optical bipolaron in different configuration of quantum confinement. Numerical and analytical results showed that when configuration changes from quantum dot and wire to well, confinement shows different effect on the formation of a bipolaron. In contrast to a bipolaron in a quantum dot or wire, the binding energy of a bipolaron in a quantum well increases with increasing con-finement, indicating that confinement favors bipolaron formation in a quantum well.
基金Project supported by the Natural Science Foundation of Hebei Province,China(Grant No.E2013407119)the Items of Institution of Higher Education Scientific Research of Hebei Province and Inner Mongolia,China(Grant Nos.ZD20131008,Z2015149,Z2015219,and NJZY14189)
文摘Based on the variational method of Pekar type, we study the energies and the wave-functions of the ground and the first-excited states of magneto-bipolaron, which is strongly coupled to the LO phonon in a parabolic potential quantum dot under an applied magnetic field, thus built up a quantum dot magneto-bipolaron qubit. The results show that the oscillation period of the probability density of the two electrons in the qubit decreases with increasing electron–phonon coupling strength α, resonant frequency of the magnetic field ωc, confinement strength of the quantum dot ω0, and dielectric constant ratio of the medium η; the probability density of the two electrons in the qubit oscillates periodically with increasing time t, angular coordinate φ2, and dielectric constant ratio of the medium η; the probability of electron appearing near the center of the quantum dot is larger, and the probability of electron appearing away from the center of the quantum dot is much smaller.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 10574082, 10474056, 90403110 and 50323006) the Natural Science Foundation of Shandong Province (Grant No. Z2005A01).
文摘The electronic properties of ground state and charged excited states of nondegenerate polydiacetylene were investigated by means of a tight-binding model. The parameters of the model were obtained by comparison of the experimental and other theoretical results. It was found that there is a stable dimerized structure of polydiacetylene in ground state and the doping induces the nonlinear excitations, such as polarons and bipolarons. In order to compare the stability of polaron and bipolaron, the creation energy and binding energy were separately defined. By neglecting the electron-electron Coulomb interaction, a bipolaron is more stable than two independent polarons.
文摘采用半经验Austin Model 1(AM1)方法,计算了齐分子吡咯聚合物(PPy)的中性态和带电态的几何结构性质.与中性态相比,带电态下其分子结构表现在C-C键长发生显著改变,单电荷掺杂导致极化子元激发;当掺杂的双电荷随机放置时,出现了两种情况:一种情况下产生双极化子,另一种情况下会产生两个分立的极化子.通过控制链的长度,可实现极化子与双极化子之间的相变,从而揭示出在有机半导体材料中实现自旋极化输运的可能性.
