共查询到18条相似文献,搜索用时 62 毫秒
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离子晶体通常具有较高的介电常数,带电粒子在晶体中会引起介电极化,其作用相当于一个可以束缚粒子的势阱.若粒子在势阱中的状态是稳定的,就有可能形成所谓的极化子与双极化子.本文采用一种简化的处理方法,将晶体材料当作各向同性的均匀介质,主要利用经典物理图像和三维量子谐振子模型,分别计算了介质中极化子与双极化子的基态能量,并进行了简要的理论分析. 相似文献
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导电聚合物中的元激发稳定性问题对于认识和理解有机材料中的自旋极化输运现象是极其重要的.针对目前存在的极化子与双极化子之间的争论,本文从半经验的Austin Model 1(AM1)方法出发,对齐分子噻吩的掺杂态进行了研究.通过对极化子和双极化子体系能量的比较,发现双极化子可以转换为极化子,从而揭示出在有机半导体材料中可以实现自旋极化输运. 相似文献
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文中用一维紧束缚模型描述铁磁金属,用一维非简并的Su-Schrieffer -Heeger (SSH)模型描述共轭聚合物,研究了在一维铁磁/共轭聚合物系统和一维CMR材料/ 聚合物系统中的电子转移和自旋转移.发现在聚合物部分没有自旋的双极化子比有自旋的极化子具有较低的能量而容易产生.然而在铁磁CMR材料/聚合物系统中极化子的产生能低于聚合物中极化子的产生能,增加了有机物中自旋极化输运的可能性. 相似文献
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本文采用扩展Hubbard模型, 加上长程关联哈密顿量,在自然边界条件下用自洽场方法研究了有限长反式聚乙炔链中极化子的问题。计算了长程电子关联对极化子的影响并计算了极化子的长程关联能。计算发现长程电子关联使极化子的位形变宽变浅(局域性减弱),在极化子区域,长程电子关联能比平均长程电子关联能要大。当链长增加到100格点以上时,电子极化子和空穴极化子的平均关联能趋于-0.1663eV,而在极化子区域,电子极化子和空穴极化子的平均关联能趋于-0.1868eV。 相似文献
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从立方型相互作用的一维分子晶体模型出发,在加入本征值平方项的近似下,运用能量极小原理和连续化近似,得到了考虑本征值平方项和立方型相互作用后一维分子晶体模型的孤子激发的修正解.在忽略了立方型相互作用和本征值平方项的近似下,孤子激发的修正解回复于通常的极化子解.并计算了孤子激发的峰宽、峰值和电子自陷势阱,分析了本征值平方项和立方型相互作用对孤子激发的峰值、峰宽和电子自陷势阱的影响. 相似文献
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文中模拟了在基态非简并聚合物中的极化子和双极化子在弱电场中的运动,研究了在不同简并参数的系统中极化子和双极化子的动力学稳定性,发现在同一个系统中,双极化子比极化子的运动速度慢,晶格振荡小; 在简并参数大的系统中,极化子和双极化子的运动速度都变慢.极化子和双极化子在弱电场下都存在饱和速度,达到饱和速度后, 电场的能量发生了转换. 相似文献
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本文模拟了基态非简并聚合物中的极化子和双极化子在强电场中的运动 ,研究了在不同简并参数的系统中极化子和双极化子的动力学稳定性,发现在强场下简并参数对极化子的稳定性影响不大,极化子晶格畸变的运动滞后于电子的运动,价带上的电子在强电场的激发下参与导电.双极化子在简并参数大的系统中较为稳定. 相似文献
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Kazuo Fujikawa 《Annals of Physics》2007,322(7):1500-1517
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Neil McCulloch Eitan Abraham 《Physica C: Superconductivity and its Applications》2009,469(21):1966-1969
The formation of bipolarons in the presence of magnetic impurities is studied theoretically. We use the extended Hubbard Su–Schrieffer–Heeger (SSH) model with Brazovskii–Kirova and Kondo interaction terms. Parameters are chosen suitably for cis-polyacetylene. A Quantum Monte Carlo (QMC) algorithm is used to study the equilibrium lattice structure and charge distribution as a function of doping level and Kondo exchange integral. The magnetic impurities can have a destructive effect on bipolaron stability, instead favouring the two polaron configuration. However by suitably adjusting the doping level, bipolarons can be stabilized over a wide range of impurity strength. 相似文献
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We use the single-path-integral to calculate the impedance function of the polaron and bipolaron in quantum confinement with the presence of the external fields. The expectation values of the classical equation of motion is considered in order to obtain the impedance function. The mobility of the polaron and bipolaron in quantum confinement is also calculated in the direction parallel and perpendicular to the magnetic field. Without trapping, we also calculate the effective mass of the bipolaron in the magnetic field. 相似文献
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The effect of longitudinal optical phonon field on the ground state and low lying-excited state energies of a hydrogenic impurity in a Zn1−xCdxSe/ZnSe strained quantum dot is investigated for various Cd content using the Aldrich-Bajaj effective potential. We consider the strain effect considering the internal electric field induced by the spontaneous and piezoelectric polarizations. Calculations have been performed using Bessel function as an orthonormal basis for different confinement potentials of barrier height. Polaron induced photoionization cross section of the hydrogenic impurity in the quantum dot is investigated. We study the oscillator strengths, the linear and third-order nonlinear optical absorption coefficients as a function of incident photon energy for 1s-1p and 1p-1d transitions with and without the polaronic effect. It is observed that the potential taking into account the effects of phonon makes the binding energies more than the obtained results using a Coulomb potential screened by a static dielectric constant and the optical properties of hydrogenic impurity in a quantum dot are strongly affected by the confining potential and the radii. It is also observed that the magnitude of the absorption coefficients increases for the transitions between higher levels with the inclusion of phonon effect. 相似文献
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The level surfaces of geometric discord for a class of two-qubit non-X states are investigated when the Bloch vectors are in arbitrary directions. The level surfaces of constant geometric discord are formed by three intersecting open tubes along three orthogc~nal directions. When Bloch vectors increase, the tubes along one or two directions shrink towards the center and may either totally disappear or the open tubes may become closed tubes when the Bloch vectors reach a critical value. In the generalized amplitude damping channel, the evolution of geometric discord shows double sudden changes when the parameter γ, increases. In the phase damping channel, the freezing phenomenon of geometric discord also exists. 相似文献