复杂体系的激发态性质及动力学过程的理论与模拟

Interpretation and modulation of the light-induced physical and chemical processes in organic molecules, biological systems, single molecule, as well as natural or artificial photosynthesis systems have become increasingly important in recent years. Theoretical studies are difficult to keep up with the pace of experiments, the main reason is that the current theoretical models have not achieved a unprecedented balance between the computational accuracy and computational efficiency for the calculations of excited states. This project aims to attack the frontiers of electronic structure calculations on the excited states of the large molecules and molecules in condense media by the development of novel theories and algorithms with respect to the time-dependent density functional theory (TDDFT). The developed methodology is expected to be computationally effective and accurate as well. The following subjects of research will be concerned. (1) Improving TDDFT itself so that it can descibe well the multiple electronic excitations and static electronic correlation which play an important role in many photophysical and photochemical processes. (2) In order to avoid the deficiencies of the finite-difference method, we develop the analytical approaches for the physical quantities related in the calculations of molecular excited-state properties, such as the excited-state energy derivatives with the external perturbed parameters, nonadiabatic couplings and transition dipole moments between the excites, spin - orbit coupling, etc. (3) The realistic environment media, such as the surrounding protein, solvents or semiconducting and metal interfaces are taken into account by combining our developed algorithms and theory based on TDDFT with the solvent models or molecular mechanism or classic nuclear dynamics or electrodynamics, etc. (4) The highly efficient software package will be developed and applied to describe the excited-state properties and ultrafast processes of molecules in solutions, photovoltaic materials and surface enhanced optical signals, etc.

解释及调制有机分子、生物体系、单分子以及自然的或者人工合成的光合作用体系中的光诱导物理及化学过程近年来变得越来越重要。但理论研究难以跟上实验的脚步，主要原因是现存的理论模型往往存在计算精度与计算效率难以匹配的问题。项目拟基于含时密度泛函理论(TDDFT)，发展快速有效的、适合于大分子或处于凝聚介质中体系的激发态性质及超快动力学过程描述的理论计算方法。具体拟开展如下工作: 改进TDDFT本身，使其可以较好地描述多重电子激发及电子的静态相关效应；基于TDDFT，发展解析方法去计算态-态之间非绝热耦合元、旋-轨耦合元以及跃迁偶极矩对核坐标的导数等等，克服有限差分方法带来的误差和计算效率低的问题; 发展基于TDDFT的杂化量子-经典方法去研究处于凝聚介质中（溶液中、半导体或惰性金属界面上）体系的激发态性质及动力学; 建立高效的计算软件，并用于研究实际重要的体系。

项目发展和应用快速有效的、适合于复杂体系激发态性质及动力学描述的算法和程序去研究实际重要的体系。项目执行期间在下面几个方面取得重要进展：（1） 结合含时密度泛函理论（TDDFT）及分子力学（MM），发展了基于TDDFT/MM计算体系电子激发态能量梯度和Hessian的解析算法及程序，使TDDFT能有效地用于研究处于溶液及蛋白质环境中分子激发态性质及动力学过程，算法已经在量子化学软件包中实现，他人可以使用；（2）发展相关函数方法, 或者结合TDDFT及经典电动力学方法发展了有效的计算复杂分子、分子-半导体/惰性金属纳米的共振Raman和vibronic谱的算法及程序；（3）结合电子结构理论和量子动力学方法探索了发生于有机分子聚集体中的单态裂分过程中涉及的量子干涉及激子相干行为与聚集体的聚集行为的关系，及它们对分裂速率的影响，这对实验合成和调控裂分效率提供了理论指导；（4）利用建立的理论及程序研究了两个荧光蛋白质的光物理光化学过程、聚集诱导的荧光增强行为、半导体异相结光解水机理、有机-无机杂化钙钛矿半导体材料的构-效关系等等，对一些微观过程和机理提供了理论解释。项目开展期间共发表标注论文22篇，培养学生9人（博士毕业5人， 硕士毕业4人），资助参加了大哟15次国际及双边学术会议。