报告题目(Title)：Ab-initio simulations of
ultrafast electron-nuclear dynamics:Paving the way to
attochemistry（从头算模拟超快电子-核动力学——开辟阿秒化学之路）
报告人(Speaker)：Victor
Despré（Université Claude Bernard Lyon 1, CNRS, Institut Lumière
Matière，里昂第一大学（克洛德·贝尔纳大学），法国国家科学研究中心，光与物质研究所）
报告时间(Time)：2026年6月3日（星期三）15:00
报告地点(Place): Zoom在线会议室：
https://us06web.zoom.us/j/85258759346?pwd=YYNArN7GfS5ynVsClgo4SvCwSdetEx.1
Meeting Chat Link
https://us06web.zoom.us/launch/jc/85258759346
Conference ID: 852 5875 9346
Password: 153372
邀请人(Inviter)：李永乐教授
主办部门：理学院物理系
摘要(Abstract)：
The
advent of attosecond physics allowed the observation and manipulation
of dynamic processes occurring within the intrinsic time scale of the
charge motion in atoms and molecules. This has opened the door to the
realization of the dream of attochemistry, namely to control chemical
reactions through the manipulation of the pure electron dynamics, the
charge migration [1], taking place in the first instants after the
excitation of the system.
Thereby, the existence of long-lasting
electronic coherences in molecular systems is the first key prerequisite
to its realization. Furthermore, understating the mechanism leading to
or preventing the loss of coherence is necessary for its development.
The
first measurement of decoherence and revival in attosecond charge
migration will be presented [2]. This dynamics occurs after excitation
of silane (SiH4) by an IR pulse. Simulations treating quantum
mechanically both the electronic and nuclear degrees of freedom
permitting the interpretation of the experimental results will be
discussed. Using these simulations, the behavior of the coherence and
the possibility to conserve coherence trough conical intersection will
be rationalized.
The second key prerequisite of the realization of
attochemistry is the understanding of how charge migration can impact
the reactivity of a molecular system. Recently, an XUV-pump IR-probe
experiment performed on adenine has demonstrated a sub 3 fs delay in its
dicationic signal. It will be shown, using multielectron wave-packet
propagation, that this delay is due to a correlation-driven charge
migration occurring in the correlation band [3] region of the molecule
that stabilizes the system. The stabilization is due to the
delocalization of the created hole and its change from σ to π character.
The generality of the observed dynamics makes correlation bands a
promising playground for the exploration of the possibilities offered by
attochemistry.
References
[1] Guiot du Doignon, C.;
Sinha-Roy, R.; Rabilloud, F.; Despré, V.: Correlation-Driven Charge
Migration Triggered by Infrared Multi-Photon Ionization, Chem. Sci. 16,
16729-16736, 2025.
[2] Matselyukh, D.; Despré, V.; Golubev, N. V.;
Kuleff, A. I.; Wörner H. J.: Decoherence and revival in attosecond
charge migration driven by non-adiabatic dynamics, Nature Physics 18,
1206-1213, 2022.
[3] Hervé, M.; Despré, V.; Castellanos Nash, P.;
Loriot, V.; Boyer, A.; Scognamiglio, A.; Karras, G.; Brédy, R.;
Constant, E.; Tielens, A. G. G. M.; Kuleff, A. I.; Lépine, F.: Ultrafast
dynamics of correlation bands following XUV molecular photoionization,
Nature Physics 17, 327-331, 2021.
阿秒物理学的问世，使得人们能够观测和操控发生在原子与分子电荷运动内禀时间尺度内的动力学过程。这为阿秒化学梦想的实现打开了大门，即通过对系统激发后最初瞬间发生的纯电子动力学——电荷迁移——的操控来控制化学反应。
因此，分子体系中长寿命电子相干性的存在，是实现该目标的第一个关键前提。此外，理解导致相干性丧失或阻止其丧失的机制，对于阿秒化学的发展亦是必要的。
本文将介绍阿秒电荷迁移中退相干与恢复的首次测量。该动力学过程发生在硅烷(SiH₄)被红外脉冲激发之后。文中将讨论对电子和核自由度均作量子力学处理的模拟，正是这些模拟使得实验结果得以被解释。利用这些模拟，可以对相干性的行为以及相干性通过圆锥交叉得以保持的可能性作出合理解释。
实现阿秒化学的第二个关键前提是理解电荷迁移如何影响分子体系的反应活性。最近，在腺嘌呤上进行的极紫外泵浦–红外探测实验在其双阳离子信号中观测到了低于3飞秒的延迟。利用多电子波包传播计算，将展示该延迟源于分子关联能带区域中发生的关联驱动电荷迁移，这一过程使体系趋于稳定。该稳定化源于所产生空穴的离域化，以及其特征从σ向π的转变。所观测到的动力学具有普适性，这使得关联能带成为探索阿秒化学所提供可能性的广阔平台。