Marracino Paolo, Paffi Alessandra, d'Inzeo Guglielmo
Rise Technology S. R. L., L. Re Paolo Toscanelli 170, 00121 Rome, Italy.
University of Rome "La Sapienza", DIET, Rome, Italy.
Phys Chem Chem Phys. 2022 May 18;24(19):11654-11661. doi: 10.1039/d1cp04466d.
Many approaches for calculation of the field-dependent electric properties of water solutions rely on the Onsager and Kirkwood theories of polar dielectrics. Such basic theories implicitly consider the electric field intensity to fulfill the so-called 'weak field conditions', to produce a linear response in the system. In this work we made use of molecular dynamics simulations to investigate possible non-linear effects induced by high intensity electric fields, specifically continuous wave bursts with nanosecond duration, comparing them with the ones predicted by the theory. We found that field intensities above 0.15 V nm produce remarkable nonlinear responses in the whole 100 MHz-100 GHz frequency window considered, with the onset of higher order polarization signals, which are the clear fingerprint of harmonic distorsions. That non-linear response turned out to depend on the considered frequency. We finally show that MD outcomes are consistent with a modelization based on an extended formulation of the Langevin function including a frequency-dependent parameter.
许多计算水溶液场依赖电性质的方法都依赖于极性电介质的昂萨格和柯克伍德理论。这些基础理论隐含地认为电场强度满足所谓的“弱场条件”，从而在系统中产生线性响应。在这项工作中，我们利用分子动力学模拟来研究高强度电场（特别是持续时间为纳秒的连续波脉冲）诱导的可能的非线性效应，并将其与理论预测的效应进行比较。我们发现，在所考虑的整个100 MHz - 100 GHz频率窗口内，高于0.15 V/nm的场强会产生显著的非线性响应，并伴随着高阶极化信号的出现，这是谐波畸变的明显特征。结果表明，这种非线性响应取决于所考虑的频率。我们最终表明，分子动力学模拟结果与基于包含频率相关参数的朗之万函数扩展公式的模型化结果一致。
