Chaves Anderson S, González-Romero Robert Luis, Meléndez Juan J, Antonelli Alex
Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP, 13083-859 Campinas, São Paulo, Brazil.
Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Ctra. de Utrera, km. 1, 41013 Sevilla, Spain.
Phys Chem Chem Phys. 2021 Jan 21;23(2):900-913. doi: 10.1039/d0cp05022a.
Efficient ab initio computational methods for the calculation of the thermoelectric transport properties of materials are of great interest for energy harvesting technologies. The constant relaxation time approximation (CRTA) has been largely used to efficiently calculate thermoelectric coefficients. However, CRTA usually does not hold for real materials. Here we go beyond the CRTA by incorporating realistic k-dependent relaxation time models of the temperature dependence of the main scattering processes, namely, screened polar and nonpolar scattering by optical phonons, scattering by acoustic phonons, and scattering by ionized impurities with screening. Our relaxation time models are based on a smooth Fourier interpolation of Kohn-Sham eigenvalues and its derivatives, taking into account non-parabolicity (beyond the parabolic or Kane models), degeneracy and multiplicity of the energy bands on the same footing, within very low computational cost. In order to test our methodology, we calculated the anisotropic thermoelectric transport properties of the low temperature phase (Pnma) of intrinsic p-type and hole-doped tin selenide (SnSe). Our results are in quantitative agreement with experimental data, regarding the evolution of the anisotropic thermoelectric coefficients with both temperature and chemical potential. Hence, from this picture, we also obtained the evolution and understanding of the main scattering processes of the overall thermoelectric transport in p-type SnSe.
用于计算材料热电输运性质的高效从头算计算方法对于能量收集技术具有重要意义。恒定弛豫时间近似（CRTA）已被广泛用于高效计算热电系数。然而，CRTA通常不适用于实际材料。在此，我们超越了CRTA，纳入了主要散射过程温度依赖性的实际k相关弛豫时间模型，即光学声子的屏蔽极化和非极化散射、声学声子散射以及带屏蔽的电离杂质散射。我们的弛豫时间模型基于科恩 - 沈（Kohn-Sham）本征值及其导数的平滑傅里叶插值，在非常低的计算成本下，同等考虑了非抛物性（超越抛物或凯恩模型）、能带的简并性和多重性。为了测试我们的方法，我们计算了本征p型和空穴掺杂的硒化锡（SnSe）低温相（Pnma）的各向异性热电输运性质。关于各向异性热电系数随温度和化学势的演变，我们的结果与实验数据在定量上一致。因此，从这个角度，我们还获得了p型SnSe中整体热电输运主要散射过程的演变及理解。
