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基于极化子和双极化子的物理图像,采用无拟合参数的巨正则统计方法计算了Si掺杂的AlxGa1-xAs的导带载流子浓度,计算得到的理论结果从高温到低温都与实验结果定量一致.计算证实了AlxGa1-xAs:Si中的DX中心的基态DX-是电子-晶格相互作用产生的负电双极化子.处于热平衡状态时,施主Si在AlxGa1-xAs中除了电离状态,处于不同晶格构型的单、双极化子态共存,低温时双极化子态被冻结;光照下发生持续光电导时,双极化子态变成单极化子态同时向导带释放一个电子,此过程伴随着进一步的晶格弛豫.理论与实验的对照说明单电子局域的DX0态在热平衡时并不能稳定存在,这和提出的双极化子机制是完全一致的. 相似文献
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基于Lee-Low-Pines幺正变换,采用Pekar类型变分法研究了抛物量子点中强耦合磁双极化子的内部激发态性质,当考虑自旋和外磁场影响时,推导出二维量子点中强耦合磁双极化子基态的能量E0,声子平均数ˉN0以及第一激发态的能量E1,声子平均数ˉN1随量子点受限强度ω0,介电常数比η,电子-声子耦合强度α和磁场的回旋共振频率ωC的变化规律.结果表明,磁双极化子的基态能量E0和第一激发态能量E1由两电子的单粒子能量E E,两电子间库仑相互作用能E C,电子自旋与磁场相互作用能E s和电子-声子相互作用能E e-ph四部分组成;单粒子"轨道"运动与磁场相互作用导致了第一激发态能级E1分裂为E(1+1)1,E(1-1)1两条,而电子自旋-磁场相互作用的效应又使基态和第一激发态的各能级均产生了三条"精细结构";ˉN0和ˉN1随ω0,α和ωc的增加而增大,E e-ph的取值总是小于零,其绝对值随α,ω0和ωc的增加而增大;电子-声子相互作用的效应是束缚态磁双极化子形成的有力因素,而限定势和电子之间的库仑排斥能的存在不利于束缚态磁双极化子的形成;能量为E(1-1)1的磁双极化子要比能量为E(1+1)1的磁双极化子更容易且更稳定地处于束缚态. 相似文献
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利用改进的Ginder-Epstein模型研究聚苯胺黑的双极化子态,给出其键序波幅、芳环扭角、电子能级、理论吸收谱和电荷分布,并与极化子进行对比.结果发现双极化子激发能为3.08 eV,晶格驰豫宽度涉及12格点与极化子相当;键交错驰豫深度大约为极化子的2倍,畸变中心芳环扭角高达68.35°大于极化子中心扭角的2倍.两个能隙态几乎简并,吸收谱低能峰为1.6 eV. 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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We have investigated numerically the pairing instabilities of Gutzwiller wavefunctions. These are equivalent to a certain form of the resonant valence bond wavefunction. The case considered is a nearly half-filled two dimensional band with interactions given by a Hubbard model with large on-site Coulomb interactions. We find that the paramagnetic normal state is unstable tod-wave pairing but stable againsts-wave pairing. The antiferromagnetic state is marginally stable against both types of pairing. These results can be explained as an interference effect resulting in enhanced antiferromagnetic spin correlation in the paired state. 相似文献
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A kinetic model of the interactions between operators and regulators is developed to study the stabilities of genetic states and lysogeny/lysis switch in Eschemchia coli infected by bacteriophage lambda. Using adiabatic approximation, the kinetic evolutions of mRNA and regulator concentrations can be deduced from operators' equations. Furthermore, the stability of each state of the system is studied. The results show that the lysogenic state switches to the lytic state through two bifurcations: one from a single stable state to a three-point state, and the other from a three-point state to a single stable state. Then we indicate that the property of the lysogeny/lysis switch satisfies the topological characteristics theorem. Finally, the influence of the left operators on the lysogeny/lysis switch is briefly discussed. The results show that the cooperativity of the CI2 bound to left and right operators makes the lysogenic state more stable. 相似文献
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We report on a light‐induced bulk defect activation and subsequent deactivation in boron doped float‐zone silicon that can be described by a 3‐state model. During treatment at elevated temperature and illumination, a sample first converts from an initial high lifetime state into a degraded low lifetime state and then shows a recovery reaction leading to a third high lifetime state that is then stable under degradation conditions. Furthermore, it is shown that reverse reactions into the initial state appear to be possible both from the degraded as well as the regenerated state. An injection dependent analysis of lifetime data yields a defect capture cross section ratio of ~20 suggesting a positively charged defect. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
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《Physics letters. A》1988,131(2):115-118
Starting from a simple one-dimensional model for many-electron and phonon interacting systems we have shown that in order to arrive at a stable minimum of the total energy the ordinary polaronic state must be replaced by the squeezed polaronic state in which the phonon subsystem is in the two-phonon coherent state. 相似文献
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We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius ≈10(-18) m. The vacuum remains stable in our model, because neutral strings are not energetically favored. 相似文献
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The electronic properties of ground state and charged excited states of non-degenerate 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. 相似文献
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对化学自由能模型进行系统性的研究,着重分析化学反应动态平衡条件下粒子组分的求解方案,提出应用模拟退火算法寻找自由能密度函数极小值点的求解方案.该方案同时解决了两个难题:1)在一级相变区化学势平衡方程组可能遇到多个解而无法甄别其物理意义.通过模拟退火算法定位到自由能密度函数曲面的最低点,因而可从多个解中甄别出稳定的热力学平衡态.2)模拟退火算法用随机的"热涨落"消除初值敏感性,因而可采用同一套初值计算不同的温度密度点,为实现宽区域上大量温度密度点的连续快速计算奠定基础.作为该平衡态求解方案的应用,计算氦流体在"等离子相变"区的物态方程,揭示了丰富的"等离子相变"现象,并与第一性原理计算揭示的氢流体"液液相变"现象进行类比. 相似文献
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C. Gruber 《Journal of statistical physics》1976,14(1):81-86
It is shown that there exists a phase transition associated with a singularity of the free energy for a model such that for all temperatures the equilibrium state is unique and thus stable with respect to boundary perturbations. It is also shown on this model that there exist phase transitions without symmetry breakdown, which can be related to a phase transition with symmetry breakdown on an equivalent model. 相似文献