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本文基于从头算R-矩阵方法，在固定核近似下，采用单态密耦合（Close Couple,CC）模型，研究了低能电子与 C4- 负离子的散射过程。研究结果预测了该负离子四种异构体在0到12 eV的能区内的电子弹性散射积分截面（integral scattering cross section,ICS），研究了存在的共振态以及构型变化对共振态位置与宽度的影响。此外还对理论结果与现有实验数据进行了细致的比较和分析，结果表明，实验观测到的8.8 eV共振峰主要是异构体A的$\Sigma_u^{+}$和$\Sigma_u^{-}$共振态的贡献以及少部分来自异构体C的A2共振态的贡献。散射截面上揭示了异构体A存在五个共振态，异构体B有三个共振态，异构体C和D各存在四个共振态。最后，我们根据玻尔兹曼分布计算了不同温度下各异构体的布居，模拟了在常温条件下C4-的低能电子弹性散射积分截面，与已有的实验结果符合较好。同时我们还发现在3.3 eV的低能区处存在一个宽度为0.20 eV的势形共振态，为实验的进一步证实提供了理论参考。This paper reports low-energy electron scattering with C4- anions with the ab initio R-matrix method in the single state close-coupling (CC) model and the fixed-nuclei approximation. We predicts the elastic integral scattering cross sections (ICS) of the four conformers for C4- ions in the energy range of 0< E ≤12eV and discusses effect of configuration changes on the position and width of the resonances. Additionally, we compare and analyze the theoretical results and experimental data. The results indicate that the experimentally observed resonant peak at 8.8 eV is mainly from the $\Sigma_u^{+}$ and $\Sigma_u^{-}$ resonances of the conformer A and the A2 resonance of the conformer C. The scattering cross-section reveals that the conformer A has five resonant states, and the conformer B has three resonances, while C and D each have four resonances. Finally, we used the Boltzmann distribution to calculate the population of different conformers at different temperatures, and simulated the low-energy electron elastic integrated scattering cross-section at room temperature, which is in good agreement with available experimental results. We also found a shape resonance at 3.3 eV with a width of 0.20 eV in our total cross sections, which is not detected in the available experimental results. This provides a new chance for the measurement.
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Keywords:
- Electron scattering /
- Conformers of C4- ions /
- R-matrix method /
- Resonance /
- Cross Section
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