AI 中文总结
该研究提出基于轨迹的从头算方法计算载流子俘获率，通过有限温度晶格动力学关联函数重构相关物理量，揭示有限温度构型系综是缺陷辅助载流子俘获的关键，且在不同材料中表现出不同特性。
AI 中文摘要
缺陷辅助的载流子俘获通常在非辐射多声子（NMP）理论中，采用平衡缺陷结构的简正模式进行描述。当有限温度下的晶格涨落探索到无法用固定简正模式基表示的构型时，该描述就变得不充分了。本文提出一种基于轨迹的从头算方法，用于计算载流子俘获率，该方法可直接从有限温度晶格动力学的关联函数中重构晶格弛豫和电子-晶格耦合矩阵元。对于谐波区域内GaN中C_N处的空穴俘获，该方法重现了静态NMP结果，包括模式混合，且与实验一致。相比之下，对于SiO_2中的氧空位，热采样的势能面比零温度简正模式的谐波展开要软得多，这显著改变了晶格弛豫和电子-晶格耦合，并导致俘获系数及其温度依赖性发生明显变化。这些结果表明，有限温度构型系综而非仅声子占据态，是缺陷辅助载流子俘获的关键要素。
英文摘要
Defect-assisted carrier capture is commonly described within nonradiative multiphonon (NMP) theory using normal modes of the equilibrium defect structure. This description becomes inadequate when finite-temperature lattice fluctuations explore configurations that cannot be represented by a fixed normal-mode basis. Here, we present a trajectory-based method for calculating carrier capture rate from first principles, which allows lattice relaxation and electron--lattice coupling matrix element to be reconstructed directly from correlation functions of finite-temperature lattice dynamics. For hole capture at C$_\mathrm{N}$ in GaN within harmonic regime, the method reproduces static NMP results including mode mixing and agrees with experiment. For oxygen vacancy in SiO$_2$, by contrast, the thermally sampled potential energy surface is substantially softer than the zero-temperature normal-mode harmonic expansion, strongly modifying the lattice relaxation and electron--lattice coupling, and producing pronounced changes in both the capture coefficient and its temperature dependence. These results establish the finite-temperature configurational ensemble, rather than phonon occupations alone, as an essential ingredient of defect-assisted carrier capture.
