Development, benchmarking and application of improved quantum-classical trajectory surface-hopping methods for the ab initio simulation of photoinduced hydrogen-atom transfer reactions and the computation of time-resolved spectroscopic signals

涉及多原子分子中非绝热耦合电子势能表面的光化学反应动力学的计算处理具有挑战性，并且由于高效计算方法的发展和强大计算资源的可用性，直到最近才成为可能。由于电子势能表面上经典核动力学的计算成本仅随自由度的数量线性增加，混合量子-经典计算方法对复杂系统的光化学动力学模拟具有吸引力，其中电子以量子力学方式描述，原子核以经典方式描述。本项目的目标是进一步发展、对标和应用改进的准经典轨迹表面跳跃方法，用于非绝热光化学过程的计算模拟和时间分辨光谱信号的计算。在第一个资助期，我们开发并实现了一种新的鲁棒和高效的表面跳跃算法，该算法基于圆锥交叉口非绝热转移概率的Landau-Zener公式。通过与光物理和光化学动力学多态多模模型的精确量子动力学计算进行比较，对这种准经典方法的准确性进行了严格检验。我们开发了一个基于landau - zener表面跳跃算法的全维动态模拟光化学动力学的计算机程序，使用二阶代数图解构造（ADC(2)）电子结构方法从头计算能量和梯度。在第二个资助期，我们将超越非平衡电子居群概率的计算，并探索对具有超快非绝热动力学的系统的时间和频率分辨光谱信号进行精确准经典模拟的可能性。改进的表面跳变方法的主要化学应用将是从头开始探索氮化碳材料光催化氧化水的激发态质子耦合电子转移（PCET）反应，这是目前太阳能转换研究的热点。

The computational treatment of photochemical reaction dynamics involving nonadiabatically coupled electronic potential-energy surfaces in polyatomic molecules is challenging and has only recently become possible due to the development of efficient computational methods and the availability of powerful computing resources. Because the computational cost of classical nuclear dynamics on electronic potential-energy surfaces increases only linearly with the number of degrees of freedom, mixed quantum-classical computational methods, in which the electrons are described quantum mechanically and the nuclei classically, are attractive for the simulation of the photochemical dynamics of complex systems. The goal of this project is the further development, benchmarking and application of improved quasi-classical trajectory surface-hopping methods for the computational simulation of nonadiabatic photochemical processes and the calculation of time-resolved spectroscopic signals. In the first funding period, we developed and implemented a novel robust and efficient surface-hopping algorithm which is based on the Landau-Zener formula for nonadiabatic transition probabilities at conical intersections. The accuracy of this quasi-classical method was critically examined by comparison with exact quantum dynamics calculation for multi-state multi-mode models of photophysical and photochemical dynamics. We developed a computer program for full-dimensional on-the-fly simulations of photochemical dynamics with the Landau-Zener-based surface-hopping algorithm, using the second-order algebraic-diagrammatic construction (ADC(2)) electronic-structure method for the ab initio calculation of energies and gradients. In the second funding period, we will move beyond the computation of nonequilibrium electronic population probabilities and explore the possibility of accurate quasi-classical simulations of time and frequency resolved spectroscopic signals for systems exhibiting ultrafast nonadiabatic dynamics. The main chemical application of the improved surface-hopping method will be the ab initio exploration of excited-state proton-coupled electron transfer (PCET) reactions involved in the photocatalytic oxidation of water with carbon nitride materials, which currently is a hot topic in solar energy conversion research.