Simulation of laser-induced coupled electron-nuclear dynamics and time-resolved harmonic spectra in complex systems
Simulation of laser-induced coupled electron-nuclear dynamics and time-resolved harmonic spectra in complex systems
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复杂系统中激光诱导耦合电子核动力学和时间分辨谐波谱的模拟
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发表时间：
2011
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通讯作者：
R. Mitrić
中科院分区：
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作者：
Polina Lisinetskaya;R. Mitrić
我们提出了一个理论方法模拟的时间分辨谐波谱，包括核动力学的影响，这是适用于复杂的系统，涉及许多核自由度。该方法是基于我们的半经典场诱导表面跳跃的方法与含时密度泛函理论的电子动力学的激光诱导的核动力学的治疗相结合。我们应用我们的方法模拟超快非绝热动力学和时间分辨谐波光谱的小银团簇（Ag{sub 2}和Ag{sub 8}），这表现出离散的类分子电子跃迁。我们表明，谐波信号是高度敏感的核动力学，因此可以用作探针的耦合电子-核动力学，这是互补的常见的泵浦-探测方法，如时间分辨光电子能谱。我们的模拟也使我们能够确定的机制和非辐射弛豫的时间尺度在“魔术”Ag{sub 8}集群，并提供了一个基本的洞察超快的金属纳米团簇的大小制度，其中“每个原子计数”的动力学。Ag{sub 8}的激发态动力学涉及从具有T{sub d}对称性的初始结构到具有D{sub 4d}对称性的二次反棱柱结构的异构化过程，该过程发生在约3600 fs的时间尺度上，并且在时间分辨谐波信号中清楚地识别。我们的理论方法是普遍适用于预测的时间分辨谐波光谱在复杂的系统与许多核自由度，并应有助于刺激新的超快实验利用谐波信号作为探针的非绝热过程中的分子系统。«少
We present a theoretical approach for the simulation of time-resolved harmonic spectra, including the effect of nuclear dynamics, which is applicable to complex systems involving many nuclear degrees of freedom. The method is based on the combination of our semiclassical field-induced surface hopping approach for the treatment of laser-induced nuclear dynamics with the time-dependent density functional theory for electron dynamics. We apply our method to the simulation of ultrafast nonadiabatic dynamics and time-resolved harmonic spectra in small silver clusters (Ag{sub 2} and Ag{sub 8}), which exhibit discrete molecularlike electronic transitions. We demonstrate that the harmonic signal is highly sensitive to the nuclear dynamics and thus can be used as a probe of coupled electron-nuclear dynamics, which is complementary to common pump-probe methods such as time-resolved photoelectron spectroscopy. Our simulations allowed us also to determine the mechanism and the time scale of nonradiative relaxation in the 'magic' Ag{sub 8} cluster and have provided a fundamental insight into ultrafast dynamics of metal nanoclusters in the size regime where 'each atom counts'. The excited-state dynamics of Ag{sub 8} involves an isomerization process from the initial structure with T{sub d} symmetry to the quadratic antiprism structure with D{sub 4d} symmetry which takes place onmore » a time scale of {approx}3600 fs and is clearly identified in a time-resolved harmonic signal. Our theoretical approach is generally applicable for the prediction of time-resolved harmonic spectra in complex systems with many nuclear degrees freedom and should serve to stimulate new ultrafast experiments utilizing harmonic signals as a probe for nonadiabatic processes in molecular systems.« less