We report the implementation of the fully relativistic exact muffin-tin orbital (EMTO) method for both first-principles electronic structure and quantum transport simulation of magnetic and nonmagnetic device materials. We consider a device-material system containing the inevitable atomic disorders in contact with different electrode materials. The Kohn-Sham Dirac equations for both cases with and without spin polarization are self-consistently solved for the central device-material system with the Green's function method. The fully relativistic charge-current density, conventional Pauli spin current density, and transmission coefficient are formulated with the nonequilibrium Green's function technique. To treat the influence of disordered defects/impurities, we combine the nonequilibrium Green's function in the Keldysh space with the coherent potential approximation, and account for the multiple disorder scattering by vertex corrections to a two-Green's-function correlator to calculate the disorder-averaged charge and spin current density. As a demonstration of the present implementation, we calculate the electronic structure of the bulk Pt, Co, and HgTe and Rashba-type surface states of Au and $\mathrm{Ag}/{\mathrm{Ag}}_2{\mathrm{Bi}}_1$ alloy surfaces. We find that the EMTO electronic structures of all the calculated systems agree well with the results of the projector-augmented wave method. The electronic charge and spin transport implementations are tested with perfect and disordered Cu/Co/Pt/Cu junctions. The important effects of interface and atomic disorders are illustrated for the spin transport in the presence of relativistic effects. The implementation of the fully relativistic EMTO-based device-material simulation provides an important tool for analyzing both the charge and spin transport through nanostructures and materials, significantly extending the capability of first-principles material design for spintronic device applications.

中文翻译：

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基于精确松饼-锡轨道的器件材料的完全相对论模拟：电荷和自旋电流

我们报告的完全相对论的精确松饼锡轨道（EMTO）方法的第一原理电子结构以及磁性和非磁性器件材料的量子传输模拟的实现。我们考虑一种器件-材料系统，该系统包含与不同电极材料接触不可避免的原子紊乱。使用格林函数方法，对于具有自旋极化和不具有自旋极化两种情况的Kohn-Sham Dirac方程，可以自洽地求解中心器件-材料系统。完全相对论的充电电流密度，传统的保利自旋电流密度和传输系数是通过非平衡格林函数技术来制定的。为了处理无序缺陷/杂质的影响，我们将非平衡Green' 函数在Keldysh空间中具有相干势近似，并且通过对两格林函数相关器的顶点校正来解决多重无序散射，从而计算出平均无序电荷和自旋电流密度。为了说明本实施方案，我们计算了Au和Ti的Pt，Co和HgTe体和Rashba型表面态的电子结构。$银/{银}_2{双}_{\mathrm{1个}}$合金表面。我们发现，所有计算系统的EMTO电子结构与投影机增强波方法的结果非常吻合。通过完美无序的Cu / Co / Pt / Cu结对电子电荷和自旋输运实现进行了测试。在存在相对论效应的情况下，说明了自旋输运对界面和原子紊乱的重要影响。完全相对论的基于EMTO的器件材料仿真的实现为分析电荷和自旋通过纳米结构和材料的传输提供了重要的工具，大大扩展了自旋电子器件应用中第一性原理材料设计的能力。