The elphbolt ab initio solver for the coupled electron-phonon Boltzmann transport equations

elphbolt is a modern Fortran (2018 standard) code for efficiently solving the coupled electron-phonon Boltzmann transport equations from first principles. Using results from density functional and density functional perturbation theory as inputs, it can calculate the effect of the non-equilibrium phonons on the electronic transport (phonon drag) and non-equilibrium electrons on the phononic transport (electron drag) in a fully self-consistent manner and obeying the constraints mandated by thermodynamics. It can calculate the lattice, charge, and thermoelectric transport coefficients for the temperature gradient and electric fields, and the effect of the mutual electron-phonon drag on these transport properties. The code fully exploits the symmetries of the crystal and the transport-active window to allow the sampling of extremely fine electron and phonon wave vector meshes required for accurately capturing the drag phenomena. The coarray feature of modern Fortran, which offers native and convenient support for parallelization, is utilized. The code is compact, readable, well-documented, and extensible by design.

elphbolt 是一款基于现代 Fortran（2018 标准）开发的专用代码，用于从第一性原理出发高效求解耦合电子-声子玻尔兹曼输运方程（Boltzmann transport equations）。该代码以密度泛函理论（density functional theory）与密度泛函微扰理论（density functional perturbation theory）的计算结果作为输入，可通过完全自洽的方式，计算非平衡声子对电子输运的影响（声子拖拽（phonon drag））以及非平衡电子对声子输运的影响（电子拖拽（electron drag）），且严格遵循热力学约束。其支持针对温度梯度与电场的晶格、电荷及热电输运系数的计算，同时可分析电子-声子相互拖拽对上述输运特性的调控作用。本代码充分利用晶体对称性与输运活性窗口（transport-active window），能够采样高精度捕捉拖拽现象所需的极精细电子与声子波矢网格。此外，现代 Fortran 原生提供的协数组（coarray）特性为并行化提供了便捷的原生支持，已被该代码全面采用。该代码设计紧凑、可读性优异、文档完备且易于扩展。