Nonequilibrium processes from generalized Langevin equations: Realistic nanoscale systems connected to two thermal baths
Nonequilibrium processes from generalized Langevin equations: Realistic nanoscale systems connected to two thermal baths
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DOI：
10.1103/physrevb.93.174303
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发表时间：
2015-12
影响因子：
3.7
通讯作者：
H. Ness;A. Genina;L. Stella;Christiane S. Lorenz;L. Kantorovich
中科院分区：
文献类型：
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作者：
H. Ness;A. Genina;L. Stella;Christiane S. Lorenz;L. Kantorovich
推广了广义朗格万方程（GLE）方法[L]。斯特拉，C. D.洛伦兹和L.坎特罗维奇，物理学家。Rev. B 89, 134303(2014)]来模拟一个中央古典区域，连接两个不同温度的现实温泉浴场。在这种非平衡条件下，通过中央系统在两个浴槽之间建立了热流。GLE- 2b （GLE双浴池）方案使我们能够对耗散中心系统及其周围的浴池进行真实的描述。在原始GLE方法的基础上，对扩展的Langevin动力学格式进行了修改，以考虑对应于每个槽的振动特性映射的两组辅助自由度。然后利用这些辅助变量求解中心区域的非马尔可夫耗散动力学。所得到的算法被用于研究连接两个槽的短铝纳米线的模型。将使用GLE-2B方法的模拟结果与使用标准恒温方法（基于markov Langevin和Nose-Hoover恒温器）进行的其他模拟结果进行比较。我们专注于稳态状态和研究系统内局部温度分布的建立。与先前的研究一致，对获得平坦轮廓或温度梯度的条件进行了详细的检查。结果表明，GLE-2B方法能够在单一方案中处理两种差异很大的热输运体系，即无温度梯度的弹道系统和有温度梯度的扩散系统。
We extend the generalized Langevin equation (GLE) method [L. Stella, C. D. Lorenz, and L. Kantorovich, Phys. Rev. B 89, 134303 (2014)] to model a central classical region connected to two realistic thermal baths at two different temperatures. In such nonequilibrium conditions a heat flow is established, via the central system, in between the two baths. The GLE-2B (GLE two baths) scheme permits us to have a realistic description of both the dissipative central system and its surrounding baths. Following the original GLE approach, the extended Langevin dynamics scheme is modified to take into account two sets of auxiliary degrees of freedom corresponding to the mapping of the vibrational properties of each bath. These auxiliary variables are then used to solve the non-Markovian dissipative dynamics of the central region. The resulting algorithm is used to study a model of a short Al nanowire connected to two baths. The results of the simulations using the GLE-2B approach are compared to the results of other simulations that were carried out using standard thermostatting approaches (based on Markovian Langevin and Nose-Hoover thermostats). We concentrate on the steady-state regime and study the establishment of a local temperature profile within the system. The conditions for obtaining a flat profile or a temperature gradient are examined in detail, in agreement with earlier studies. The results show that the GLE-2B approach is able to treat, within a single scheme, two widely different thermal transport regimes, i.e., ballistic systems, with no temperature gradient, and diffusive systems with a temperature gradient.