TRACK: A python code for calculating the transport properties of correlated electron systems using Kubo formalism

Exploring the transport properties of different materials brings new avenue for basic understanding of emergent phenomena and practical applications in many different fields. Here, we report a program named as TRACK (TRAnsport properties for Correlated materials using Kubo formalism) which is written in Python 3 for calculating temperature dependent electrical conductivity, electronic part of thermal conductivity, Seebeck coefficient and Lorenz number. In this code, Kubo linear-response formalism is utilized for computing these parameters using both interacting and non-interacting electronic structure methods. The formula for transport coefficients is accordingly modified to obtain the transport parameters under relaxation time approximation using band-theory. The basic inputs of this program are the structural information, dense k-points sampling in the irreducible part of the Brillouin zone and the information of velocity matrix elements, which can be calculated using third-party ab-initio package. TRACK is expected to calculate the transport properties of different class of materials. The code has been benchmarked by performing calculation on three different types of materials namely Vanadium (V), FeSi and LaCoO3, which are metal, semiconductor and Mott insulator, respectively. The temperature dependent behaviour of the transport coefficients for these materials show fairly good agreement with the corresponding experimental data.

探究不同材料的传输性质为基本理解涌现现象及其在众多不同领域的实际应用开辟了新的途径。本研究报告了一款名为TRACK（利用Kubo公式的相关材料传输性质）的程序，该程序采用Python 3编写，用于计算温度依赖性电导率、热导率的电子部分、塞贝克系数和洛伦兹数。在此代码中，采用Kubo线性响应公式，结合相互作用和非相互作用电子结构方法计算这些参数。根据能带理论，对传输系数的公式进行了相应修改，以在弛豫时间近似下获得传输参数。本程序的基本输入包括结构信息、布里渊区不可约部分的密集k点采样以及速度矩阵元素信息，这些信息可通过第三方第一性原理包计算得出。TRACK旨在计算不同类别的材料传输性质。该代码已通过在三种不同类型的材料上进行计算进行了基准测试，这三种材料分别为钒（V）、FeSi和LaCoO3，分别代表金属、半导体和Mott绝缘体。这些材料的传输系数的温度依赖性表现出与相应实验数据的良好一致性。