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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >On the 'Atomic' Polarizabilities in Small Si_n Clusters and the Dielectric Constant of Bulk Silicon
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On the 'Atomic' Polarizabilities in Small Si_n Clusters and the Dielectric Constant of Bulk Silicon

机译：Si_n团簇中的“原子”极化率与体硅的介电常数

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Applying the classical discrete reaction field (DRF) approach, which includes a treatment for the solution of the many-body polarization in complex systems, we calculated the mean atomic polarizability for a Si atom from the known molecular polarizability of Si3. With only this parameter (6.16 A~3, i.e., close to the free atom value), and the geometries as input, the effective atomic mean polarizabilities and their averages (<α>_n = <α>(n)) for the series Si4-Si_(10) were calculated and found to be in excellent agreement with theoretical and experimental values. These <α>_n are larger than the bulk value of 3.7 A~3. We used the same input parameter for (by hand) constructed model systems up to n = 4950 with various geometries. For the larger clusters with the diamond lattice, we obtained the bulk value, implying that we "predicted" the dielectric constant of silicon almost from first principles. However, even the largest system is still too small for considering it as a real dielectric. In other lattices (primitive and face centered cubic), the <α>_n are significantly smaller than 3.7 A~3, which we attribute to the tighter packing in these lattices in comparison with that of the diamond structure. The behavior in all these systems can be easily understood by accounting properly for the local fields and for damping the interaction between induced dipoles. We show that there is no need for additional (e.g., "charge transfer") parameters.
机译：应用经典的离散反应场（DRF）方法，其中包括解决复杂系统中多体极化的方法，我们从已知的Si3分子极化率计算了Si原子的平均原子极化率。仅使用该参数（6.16 A〜3，即接近自由原子值），并将几何作为输入，则有效原子平均极化率及其平均值（<α> _n = <α>（n）/ n）为计算得出Si4-Si_（10）系列与理论值和实验值非常吻合。这些 _n大于3.7 A〜3的整体值。对于具有不同几何形状的n = 4950的构建模型系统，我们使用相同的输入参数。对于具有菱形晶格的较大簇，我们获得了体积值，这意味着我们几乎是根据第一原理“预测”了硅的介电常数。但是，即使是最大的系统，仍然无法将其视为真正的电介质。在其他晶格（原始晶格和面心立方）中，<α> _n显着小于3.7 A〜3，这归因于与金刚石结构相比，这些晶格中的堆积更紧密。通过适当考虑局部场并衰减感应偶极之间的相互作用，可以轻松理解所有这些系统中的行为。我们表明，不需要其他参数（例如“电荷转移”）。

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