ABSTRACT In this paper, we perform molecular dynamics simulations of a dielectric fluidic material composed of permanent molecular dipoles. The dielectric spectrum features two peaks at lower frequencies than the system phonon frequency. The primary peak is observed at all temperatures studied and shifts toward lower frequencies as the temperature decreases. During this shift, the secondary peak emerges with a higher peak frequency than the primary peak. The secondary peak amplitude increases as the temperature decreases. Both peaks are dependent on the wavevector; in the small wavevector regime, the primary peak is shifted to higher frequencies as the wavevector squared and the secondary peak amplitude increases as the wavevector increases, but shows no shift in frequency. From the polarisation balance equation, we propose a model for the dielectric spectrum. This captures the spectrum features, and we conjecture that the primary peak is due to dipole moment correlations (Debye-type) and the secondary peak is due to the correlation between the dipole moment and a microscopic local field.

中文翻译：

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简单介电材料介电谱的机械模型

摘要 在本文中，我们对由永久分子偶极子组成的介电流体材料进行了分子动力学模拟。介电谱在比系统声子频率更低的频率处具有两个峰值。在所研究的所有温度下均观察到主峰，并随着温度降低而向较低频率移动。在这个转变过程中，次级峰出现的峰频率高于初级峰。次级峰值幅度随着温度的降低而增加。两个峰值都依赖于波矢；在小波矢范围内，主峰随着波矢的平方而向更高的频率移动，而次峰幅度随着波矢的增加而增加，但频率没有变化。从极化平衡方程，我们提出了介电谱模型。这捕获了光谱特征，我们推测主峰是由于偶极矩相关（德拜型）而次级峰是由于偶极矩与微观局部场之间的相关性。