采用基于线性响应理论的非平衡分子动力学模拟方法, 通过3体Tersoff势函数描述原子间的相互作用, 模拟了C, BN和SiC纳米管的热传导过程. 研究了轴向长度、温度和外加拉伸应变等因素对3种纳米管的轴向热导率的影响, 并对3种纳米管的导热性能进行了比较. 结果表明: 纳米管的热导率k随着轴向长度L的增加而增加,两者大致呈k∝ Lα关系, 与求解声子传输方程得到的理论解一致;纳米管的热导率随温度升高而降低; 随着轴向拉伸应变的增大, 纳米管的热导率有先增加后降低的转变趋势, 但3种纳米管的热导率发生转变时对应的拉伸应变不同; 相同条件下3种纳米管的热导率从大到小依次为: C, BN和SiC.
The Non–equilibrium molecular dynamics (NEMD) simulation method which is based on the linear response theory is applied to simulate the thermal conduction process of C, BN and SiC nanotubes. The three–body Tersoff potential is used to simulate the interactions among atoms. The effects of axial length, temperature and tensile strain on the axial thermal conductivity of the three kinds of nanotubes are investigated, and their thermal conductivities are compared and analyzed. The simulation results show that the axial thermal conductivity increases as the axial length increases, and exhibits a relationship k ∝ Lα that is in agreement with the solution of Boltzmann-Peierls phonon transport equation (B–P equation). It is found that the thermal conductivity of nanotube decreases with the increase of temperature. As the tensile strain increases, the thermal conductivity of nanotubes show an slight increase first, and then decreases. But, the corresponding tensile strains at which the tendency of thermal conductivity of the three nanotubes changes are different. Under the same conditions, the sequence of thermal conductivity from the biggest to the smallest is in the order of carbonanotues, boron nitride naotubes and carbon silicon nanotues.
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