发表机构
Technion - Israel Institute of Technology（以色列理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过从头算含时密度泛函理论揭示，阿秒电荷迁移的时间尺度由分子跃迁偶极矩决定，而非电子关联，为调控电荷迁移提供了新途径。
AI 中文摘要
阿秒电荷迁移（CM）是一种超快过程，当分子被超短激光脉冲照射时，会产生一个局域空穴。该空穴在分子中快速传播，产生电流并将电荷转移至分子骨架。CM是太阳能转换、光合作用和辐射损伤中的关键因素。尽管其重要性和研究密集，CM的基本物理和化学机制仍未完全理解。特别是，需要更深入地理解关联在动力学中的作用，以及哪些化学属性决定CM的时间尺度。在此，我们利用从头算含时密度泛函理论研究基准分子BrC$_4$H中的CM。我们在电子和结构层面，包括使用不同电子关联程度的理论，全面探索了不同初始条件下的CM。我们发现了一个普适行为，即空穴矩（与实验观测量相关）的主导频率大致独立于所有这些特征。相反，空穴密度演化的时间尺度确实随化学条件和关联水平而变化。利用一种半解析理论，在阳离子参考系中重构空穴矩，我们表明CM的阿秒时间尺度由分子偶极矩决定，这些偶极矩通过类似于光学选择规则的机制滤除特定频率响应。我们的结果为CM物理提供了重要见解，这应有助于解释阿秒实验和通过调控跃迁偶极矩来工程化CM时间尺度。
英文摘要
Attosecond charge migration (CM) is an ultrafast process occurring when a molecule is irradiated by ultrashort laser pulses, creating a localized hole. The hole propagates rapidly through the molecule, generating electric currents and transferring charge across the molecular backbone. CM is a key ingredient in solar energy conversion, photosynthesis, and radiation damage. Despite its importance and intensive research, the fundamental physical and chemical mechanisms of CM remain not fully understood. Especially, a deeper insight into the role correlations play in the dynamics, and which chemical attributes determine CM timescales, is needed. Here we study with \textit{ab-initio} time-dependent density functional theory CM in the benchmark molecule, BrC$_4$H. We thoroughly explore CM under different initial conditions at the electronic and structural levels, including with theories of varying degrees of electronic correlations. We uncover a universal behavior where the hole moment (connecting to experimental observables) dominant frequency is roughly independent of all of these characteristics. In contrast, the timescales of the hole density evolution do vary with the chemical conditions and level of correlations. Employing a semi-analytical theory that reconstructs the hole moments in the cationic reference frame, we show that the attosecond timescale of CM is determined by molecular dipoles that filter out specific frequency responses with an analogy to optical selection rules. Our results provide essential insight into CM physics, which should be useful for interpreting attosecond experiments and engineering CM timescales by tailoring transition dipoles.
