Heat transport in silicon from first-principles calculations
Heat transport in silicon from first-principles calculations
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DOI：
10.1103/physrevb.84.085204
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发表时间：
2011-08-23
影响因子：
3.7
通讯作者：
Stokes, Harold T.
中科院分区：
文献类型：
--
作者：
Esfarjani, Keivan;Chen, Gang;Stokes, Harold T.
利用从超原胞密度泛函计算中提取的谐波和非谐波力常数，我们开发了一种相对简单但通用的方法来计算任何晶体的热力学和热性质。首先，我们从简谐力常数、三次力常数和四次力常数出发，构造了一个分子动力学力场。它在小原子位移的限制下是精确的，因此不会受到半经验势（如Stillinger-Weber势）固有的不准确性的影响。通过使用Green-Kubo公式和分子动力学模拟，我们提取了体热导率。这种方法在高温下是准确的，其中三声子过程需要包括到更高阶，但可能会受到尺寸缩放问题的影响。接下来，我们利用微扰理论（费米黄金法则）来提取声子寿命和计算热导率。弛豫时间近似。这种方法在大多数温度下都是有效的，但会高估。在非常高的温度下，在我们的计算中忽略的高阶过程也有贡献。作为测试，这些方法被应用到体晶体硅，和结果进行了比较，并更详细地讨论了差异。所提出的方法铺平了道路，系统的方法来模拟固体中的热传输使用多尺度建模，其中由于非谐三声子过程的弛豫时间进行定量计算，除了通常的谐波特性，如声子频率和群速度。它还允许构建一个准确的体原子间相互作用势数据库。
Using harmonic and anharmonic force constants extracted from density functional calculations within a supercell, we have developed a relatively simple but general method to compute thermodynamic and thermal properties of any crystal. First, from the harmonic, cubic, and quartic force constants, we construct a force field for molecular dynamics. It is exact in the limit of small atomic displacements and thus does not suffer from inaccuracies inherent in semiempirical potentials such as Stillinger-Weber's. By using the Green-Kubo formula and molecular dynamics simulations, we extract the bulk thermal conductivity. This method is accurate at high temperatures where three-phonon processes need to be included to higher orders, but may suffer from size scaling issues. Next, we use perturbation theory (Fermi golden rule) to extract the phonon lifetimes and compute the thermal conductivity. from the relaxation-time approximation. This method is valid at most temperatures, but will overestimate. at very high temperatures, where higher-order processes neglected in our calculations also contribute. As a test, these methods are applied to bulk crystalline silicon, and the results are compared and differences are discussed in more detail. The presented methodology paves the way for a systematic approach to model heat transport in solids using multiscale modeling, in which the relaxation time due to anharmonic three-phonon processes is calculated quantitatively, in addition to the usual harmonic properties such as phonon frequencies and group velocities. It also allows the construction of an accurate bulk interatomic potentials database.