论文标题
聚合物链中的热传导：底物对热电导的影响
Heat Conduction in Polymer Chains: Effect of Substrate on the Thermal Conductance
论文作者
论文摘要
在标准分子连接中，分子结构在金属铅之间并连接到金属铅之间。了解这种分子连接中的机械调整如何改变热电导在纳米级能量运输中具有有趣的应用。在这项工作中，我们使用非平衡的分子动力学模拟来解决拉伸对由单个长链烷烃和各种金属铅组成的分子连接热传导的语音贡献的影响。发现此类连接的导热电导率比聚合物的固有导热率小得多，并且显着取决于金属铅的性质，如金属分子偶联和状态的金属振动密度所表达的那样。这种行为是可以预期的，并反映了金属分子界面处的声子光谱的不匹配。作为拉伸的函数，我们发现一种行为与早期观察到的行为相似[J.化学物理。 153，164903（2020）]用于纯聚合结构。在相对较短的电极距离处，在压缩聚乙烯链的情况下，发现分子连接的热电导量几乎保持恒定，因为一个人伸展聚合物链。在临界电极距离处，导热电导开始增加，达到完全伸展的分子连接的值。在各种金属导线之间将几个长链烷烃夹在几个长链烷烃之间也观察到类似的行为。 这些发现表明，在拉伸下，这种行为是聚合物链的内在特性，并且与界面结构没有显着相关性。
In standard molecular junctions, a molecular structure is placed between and connected to metal leads. Understanding how mechanical tuning in such molecular junctions can change heat conductance has interesting applications in nanoscale energy transport. In this work, we use nonequilibrium molecular dynamics simulations to address the effect of stretching on the phononic contribution to the heat conduction of molecular junctions consisting of single long-chain alkanes and various metal leads such as Ag, Au, Cu, Ni, and Pt. The thermal conductance of such junctions is found to be much smaller than the intrinsic thermal conductance of the polymer and significantly depends on the nature of metal leads as expressed by the metal-molecule coupling and metal vibrational density of states. This behavior is expected and reflects the mismatch of phonon spectra at the metal molecule interfaces. As a function of stretching, we find a behavior similar to what was observed earlier [J. Chem. Phys. 153, 164903 (2020)] for pure polymeric structures. At relatively short electrode distances, where the polyethylene chains are compressed, it is found that the thermal conductances of the molecular junctions remain almost constant as one stretches the polymer chains. At critical electrode distances, the thermal conductances start to increase, reaching the values of the fully-extended molecular junctions. Similar behaviors are observed for junctions in which several long-chain alkanes are sandwiched between various metal leads. These findings indicate that this behavior under stretching is an intrinsic property of the polymer chain and not significantly associated with the interfacial structures.
