声子局域化引起的反常界面温度分布
Anomalous interfacial temperature profile induced by phonon localization
摘要：
通过对功率谱密度的积分，我们得到了多段谐波和非谐波系统的温度分布，表明界面段内存在异常的负温度梯度。通过对功率谱密度的研究，我们发现这种违反直觉的现象来自于界面局域声子模的存在。谐振子模型的两个带外局域模由于不存在声子相互作用而对局域温度没有贡献，导致了凹形温度分布和过冷效应。对于非简谐模型，由于声子-声子相互作用，局域模被激发并对界面温度做出相当大的贡献，这通过检查温度累积函数清楚地示出。当非谐性相当大时，由于局域声子模完全混合，负温度梯度不存在。对孤立谐波模型的简正模分析和参与比倒数的计算结果表明了局域模的存在。
英文摘要：
Through the integration of the power spectral density, we obtain temperature profiles of both multi-segment harmonic and anharmonic systems, showing the presence of an anomalous negative temperature gradient inside the interfacial segment. Via investigating patterns of the power spectral density, we found that the counterintuitive phenomenon comes from the presence of interfacial localized phonon modes. Two out-band localized modes of the harmonic model, which make no contributions to local temperature due to the absence of phonon interactions, result in the concave temperature profile and over-cooling effect. For the anharmonic model, thanks to the phonon-phonon interactions, the localized modes are excited and make considerable contributions to interfacial temperature, which is clearly shown by examining the temperature accumulation function. When anharmonicity is considerably large, the negative temperature gradient is absent since the localized phonon modes are fully mixed. The presence of localized modes are evidently demonstrated by the inverse participation ratio and normal mode analysis for the isolated harmonic model.
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