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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Electron Localiation in Polyslane Radical Ions
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Electron Localiation in Polyslane Radical Ions

机译：聚硅烷自由基离子中的电子定位

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摘要

The localization mechanism for the excess electron and positive hole in the polysilane radical anion and cation has been investigated by means of both molecular dynamics (MD) and extended Huckel molecular orbital (EHMO) calculations. A linear oligosilane (Si_nH_(2n + 2)) (n = 32 and 64) was chosen as the model of polysilane. The geometry optimization of the polysilane at the MM2 level gave a regular all-trans form as the most stable structure. The MD calculations, started from the optimized structure, showed that the conformation most stable structure. The MD calculations, started from the optimized structure, showed that the conformation of the polysilane skeleton was gradually randomized as a function of time by thermal activation at 300 K. The conformations at 0.0, 0.05, 1.0, 1.5, and 2.0 ps were chosen as sampling points, and spin densities on the silicon atoms were calculated by the EHMO calculations at each sampling point. An excess electron and a positive hole were fully delocalized along the Si chain in the regular all-trans form (time = 0.0 ps), whereas in the disordered conformations (time not= 0) both electron and hole were completely localized on a few Si atoms (10-20 monomer units). The present calculations suggested that a continuous disorder of the Si main chain randomized by thermal energy (i.e., disordered dihedral angle of Si skeletons) is dominant in both electron and hole localization. The localization mechanism was discussed on the basis of theoretical results.
机译：通过分子动力学（MD）和扩展的Huckel分子轨道（EHMO）计算，研究了聚硅烷自由基阴离子和阳离子中过量电子和正空穴的定位机理。选择线性低聚硅烷（Si_nH_（2n + 2））（n = 32和64）作为聚硅烷模型。 MM2级别的聚硅烷的几何优化使规则的全反式形式成为最稳定的结构。从优化结构开始的MD计算表明构象最稳定的结构。从优化结构开始的MD计算表明，聚硅烷骨架的构象通过在300 K下的热活化而逐渐随时间而随机化。选择0.0、0.05、1.0、1.5和2.0 ps的构象作为采样点和硅原子上的自旋密度通过EHMO计算在每个采样点处进行计算。过量的电子和一个正空穴以规则的全反型形式（时间= 0.0 ps）沿Si链完全失域，而在无序构象（时间不= 0）中，电子和空穴都完全位于少数Si上原子（10-20个单体单元）。目前的计算表明，通过热能随机化的Si主链的连续无序（即，Si骨架的二面角无序）在电子和空穴定位中均占主导。在理论结果的基础上讨论了定位机制。

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