从头算高效非平衡电子动力学：利用库普曼斯谱函数和万尼尔定域化
Efficient nonequilibrium electron dynamics from first-principles: leveraging Koopmans spectral functionals and Wannier localization
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中文总结 AI 辅助
该研究提出一种结合库普曼斯兼容泛函与万尼尔基实时演化的从头算方法，可高效模拟超出线性区域的非平衡电子动力学，能准确探测非线性光学光谱中的激子效应，为研究固体超快强场现象提供高效途径。
中文摘要 AI 辅助
我们提出了一种用于模拟扩展系统中超出线性区域的非平衡电子动力学的高效从头算方法。该方法将能提供准确准粒子能带结构的库普曼斯兼容泛函，与在哈特里加屏蔽交换（HSEX）近似下的万尼尔基中电子密度矩阵的实时演化相结合。轨道基的定域性支持具有物理依据的近似，可在保持精度的同时显著降低计算成本和内存需求。HSEX自能的核心成分——屏蔽库仑相互作用，通过密度泛函微扰理论高效计算。我们在弱束缚和强束缚激子体系的线性区域，将该方法与实验光谱及参考格林函数计算进行了基准测试。进入非线性区域，我们研究了硅和氟化锂中的高次谐波产生（HHG）。硅的HHG光谱主要由准粒子能带结构决定，而在具有强激子效应的氟化锂中，谐波发射在激子共振处选择性增强，表明HHG探测的是关联电子-空穴激发，而非仅准粒子能带结构。与实时格林函数方法相比，该框架能以显著降低的计算成本对非线性光学光谱中的激子效应进行从头算模拟，为研究固体中的超快和强场现象提供了高效途径。
英文摘要
We present an efficient first-principles approach for simulating the nonequilibrium electron dynamics in extended systems beyond the linear regime. The method combines Koopmans-compliant functionals, which provide an accurate quasiparticle band structures, with the real-time evolution of the electronic density matrix in a Wannier basis within the Hartree plus screened exchange (HSEX) approximation. The locality of the orbital basis enables physically motivated approximations that significantly reduce both the computational cost and memory requirements while preserving accuracy. The screened Coulomb interaction, the central ingredient of the HSEX self-energy, is computed efficiently using density-functional perturbation theory. We benchmark the approach in the linear regime against experimental spectra and reference Green's function calculations for systems featuring both weakly and strongly bound excitons. Moving to the nonlinear regime, we investigate high-harmonic generation (HHG) in silicon and lithium fluoride. While in silicon the HHG spectrum is largely governed by the quasiparticle band structure, in LiF, a material featuring strong excitonics effect, the harmonic emission is selectively enhanced at excitonic resonances, suggesting that HHG probes correlated electron-hole excitations rather than solely the quasiparticle band structure. The present framework enables fully \textit{ab-initio} simulations of excitonic effects in nonlinear optical spectra at a significantly reduced computational cost compared to real-time Green's function approaches, providing an efficient route to the study of ultrafast and strong-field phenomena in solids.
