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1.
研究了链状聚合物的长短键结构呈准周期排列的电子谱。利用紧束缚近似和转移矩阵方法通过理论证明和计算表明:这种准周期排列聚合物的电子谱,当长短键长度相差很小时,具有类似于金属晶体的能带结构;相差很大时,具有无序系统一维能级结构;而对于一般情形,其电子谱与上两者均异,形成所谓的类Cantor集。这3类不同的谱结构反映在链状聚合物的宏观物理性质上也将有所不同,它无疑会影响聚合物的稳定性及相关(超)导电性能,深入研究这方面问题将有助于对有机超导的认识。 相似文献
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The minimal quantization structure is employed to investigate the quantum version of the Stackelberg duopoly with continuous distributed asymmetric information, i.e a continuous distribution while the second mover has the first mover has incomplete information that obeys complete information. It is found that the effects of the positive quantum entanglement on the outcomes exhibit many interesting features due to the information asymmetry. Moreover, although the first-mover advantage is counteracted by the information asymmetry, the positive quantum entanglement still enhances the first-mover advantage and improves the first-mover tolerance of the information asymmetry beyond the classical limit. 相似文献
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对二维晶格上的Kadanoff分块进行了全面分析,给出了划分的一般规律,得出元块选择的非任意性和含相同元块选择不惟一等结论,并给出正三角形格子和正方形格子元块中格点数目的允许值。同时,利用重整化群方法对9点,13点元块进行了计算,得到了相应的不动点和各种临界指数,并与其它计算结果进行了比较,结果表明,计算精度有随元块中所含格点数的增加而增加的趋势。 相似文献
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在有效场理论和几种不同矢量介子主导(vector meson dominance,VMD)模型的基础上,考虑介子波函数尺寸效应,引入量子色动力学(quantum chromodynamics,QCD)因子,研究了ηc→γl+l-的单达利兹衰变;计算了ηc衰变到γl+l-(l=e,μ)与双光子的相对衰变宽度,给出了相对微分衰变宽度随轻子对l+l-的不变质量谱的分布,并估计了区分不同模型需要的ηc、Jψ、ψ(3686)、hc和B介子事例数。 相似文献
6.
In addition to the phonon variable there is the phason variable in
hydrodynamics for quasicrystals. These two kinds of hydrodynamic
variables have different transformation properties. The phonon
variable transforms under the vector representation, whereas the
phason variable transforms under another related representation.
Thus, a basis (or a set of basis functions) in the representation
space should include such two kinds of variables. This makes it more
difficult to determine the physical property tensors of
quasicrystals. In this paper the group-theoretical method is given
to determine the physical property tensors of quasicrystals. As an
illustration of this method we calculate the third-order elasticity
tensors of quasicrystals with five-fold symmetry by means of basis
functions. It follows that the linear phonon elasticity is
isotropic, but the nonlinear phonon elasticity is anisotropic for
pentagonal quasicrystals. Meanwhile, the basis functions are
constructed for all noncrystallographic point groups of
quasicrystals. 相似文献
7.
The phonon dispersion relations of three kinds of 4 carbon nanotubes are calculated by using the density functional perturbation theory. It is found that the frequencies of some phonon modes are very sensitive to the smearing width used in the calculations, and eventually become negative at low electronic temperature. Moreover, two kinds of soft modes are identified for the (5,0) tube which are quite different from those reported previously. Our results suggest that the (5,0) tube remains metallic at very low temperature, instead of the metallic-semiconducting transition claimed before. 相似文献
8.
共轭聚合物中的电子可以分为π电子和σ电子两大类,当格点发生畸变时,σ电子能量的变化总是倾赂于阻碍畸变发生。因此系统是否产生畸变将取决于π电子的能量变化。我们的结果表明,对一类典型的共轭聚合物(Poly-Cn group)当n〉2时,畸变后π电子的能量变化同样倾向于阻碍畸变发生,因此,n〉2的聚合物不发生Peierls畸变,不过当考虑较远邻作用后,n为偶数的能级简并被解除,因为它们是一种偶然简并,而n为奇数的分子仍然保持能带的简并性,即无能隙能带结构。这种简并性来源于n为奇数的分子具有滑移平面对称性,因而它是内禀的。从这种意义上说,所有n〉2且为奇数的Poly-Cn群分子可能成为有机超导材料的候选物。 相似文献
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The light unflavoured meson η/η' decays are valuable for testing non-perturbative quantum chromodynamics and exploring new physics beyond the Standard Model. This paper describes a series of event generators, including η/η'→γl~+l~-, η/η'→γπ~+π~-, η'→ωe~+e~-, η→π~+π~-π~0, η/η'→π~0π~0π~0, η'→ηππ andη'→π~+π~-π~+π~-/π~+π~-π~0π~0, which have been developed for investigating η/ηdecay dynamics. For most of these generators, their usability has been validated in BESIII analyses for determining the detection efficiency, and background studies. The consistency between data and Monte Carlo shows that these generators work well in the BESⅢ simulation, and will also be useful for ongoing BESⅢ analyses and other experiments for studying η/η' physics. 相似文献