Heat transport enhanced by optical phonons in one-dimensional anharmonic lattices with alternating bonds.
Heat transport enhanced by optical phonons in one-dimensional anharmonic lattices with alternating bonds.
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DOI：
10.1103/physreve.88.052128
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发表时间：
2013-11
期刊：
影响因子：
--
通讯作者：
Daxing Xiong;Yong Zhang;Hong Zhao
中科院分区：
文献类型：
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作者：
Daxing Xiong;Yong Zhang;Hong Zhao
在晶格系统中，光学声子对热传输的影响通常被忽略，因为与声声子相比，其群速度相对较小，甚至被认为是负的，因为引入光学声子可能同时降低声声子的群速度。为了更好地理解光学声子所起的作用，我们提出了一种具有交替相互作用的一维非谐晶格模型，可以方便地调谐光学声子。我们发现，与之前的研究相比，光学声子（与非线性相配合）可以增强热力学极限内的热传递，这表明光学声子也可以发挥积极的作用。其基本机制与两种非线性激励的影响有关，即光学和间隙离散呼吸器（DB）。这些 DB 释放能量，进而促进热传输。
In lattice systems, the effects of optical phonons on heat transport are usually neglected due to their relatively small group velocities compared with acoustic phonons, or even assumed to be negative because introducing optical phonons may simultaneously reduce the group velocities of acoustic phonons. In order to well understand the role played by optical phonons, we propose a one-dimensional anharmonic lattice model with alternating interactions, where the optical phonons can be conveniently tuned. We find that in contrast to previous studies, the optical phonons (in coordination with the nonlinearities) can enhance heat transport in the thermodynamical limit, suggesting that optical phonons can also play an active role. The underlying mechanism is related to the effects of two kinds of nonlinear excitations, i.e., the optical and the gap discrete breathers (DBs). These DBs release energy and in turn facilitate heat transport.