Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542, Singapore.
J Chem Phys. 2011 Sep 14;135(10):104508. doi: 10.1063/1.3637044.
We study heat current autocorrelation function and thermal conductivity in core-shell nanowires by using molecular dynamics simulations. Interestingly, a remarkable oscillation effect in heat current autocorrelation function is observed in core-shell NWs, while the same effect is absent in pure silicon nanowires, nanotube structures, and random doped nanowires. Detailed characterizations of the oscillation signal reveal that this intriguing oscillation is caused by the coherent resonance effect of the transverse and longitudinal phonon modes. This phonon resonance results in the localization of the longitudinal modes, which leads to the reduction of thermal conductivity in core-shell nanowires. Our study reveals that a coherent mechanism can be used to tune thermal conductivity in core-shell nanowires.
我们通过分子动力学模拟研究了核壳纳米线中的热流自相关函数和热导率。有趣的是,在核壳 NWs 中观察到热流自相关函数中的显著振荡效应,而在纯硅纳米线、纳米管结构和随机掺杂纳米线中则没有观察到相同的效应。对振荡信号的详细特征分析表明,这种有趣的振荡是由横波和纵波模式的相干共振效应引起的。这种声子共振导致了纵波模式的局域化,从而导致核壳纳米线中热导率的降低。我们的研究表明,相干机制可用于调节核壳纳米线中的热导率。