基于量子修正的石墨烯纳米带热导率分子动力学表征方法

摘要

A nonequilibrium molecular dynamics model combined with quantum correction is presented for characterizing the thermal conductivity of graphene nanoribbons (GNR). Temperature effect on graphene nanoribbon thermal conductivity is revealed based on this model. It is shown that different from the decreasing dependence in classical nonequilibrium molecular dynamics simulations , an “anomaly” is revealed at low temperatures using quantum correction. Besides, the conductivity of GNR shows obvious edge and scale effects: The zigzag GNR have higher thermal conductivity than the zigzag GNR. The whole temperature range of thermal conductivity and the slope of thermal conductivity at low temperatures both show an increasing dependence of width. Boltzmann-Peierls phonon transport equation is used to explain the temperature and scale effects at low temperatures, indicating that the model constructed is suitable for a wide temperature range of accurate calculation for thermal conductivity of different chirality and width. Research provides a possible theoretical and computational basis for heat transfer and dissipation applications of GNR.%本文提出了基于量子修正的非平衡态分子动力学模型，可用于石墨烯纳米带热导率的表征。利用该模型对不同温度下，不同手性及宽度的石墨烯纳米带热导率进行了研究，结果发现：相较于经典分子动力学模型给出的热导率随温度升高而单调下降的结论，在低于Debye温度的情况下，量子修正模型的计算结果出现了反常现象。本文研究还发现，石墨烯纳米带的热导率呈现出明显的边缘效应及尺度效应：锯齿型石墨烯纳米带的热导率明显高于扶手椅型石墨烯纳米带；全温段的热导率及热导率在低温段随温度变化的斜率均随宽度的增加而增大。最后，文章用Boltzmann 声子散射理论对低温段的温度效应及尺度效应进行了阐释，其理论分析结果说明文章所建模型适合在全温段范围内对不同宽度和不同手性的热导率进行精确计算，可为石墨烯纳米带在传热散热领域的应用提供理论计算和分析依据。