Quantum chemical methods for studying photoinitiated processes in biological systems

天普大学的Spiridoula Matsika得到了化学系化学理论，模型和计算方法项目的支持，以开发和使用理论模型来理解生物系统中的光引发现象。 Matsika和她的研究小组开发了用于激发态和锥形交叉点的有效量子化学方法，这在研究光引发过程中至关重要。所提出的方法通过使用从高重数态获得的自然轨道代替传统的多构型轨道，提高了多参考构型相互作用（MRCI）的效率。 初步结果表明，这种方法大大降低了计算成本相比，传统的MRCI的准确性没有损失。目前也正在为这种方法开发替代品。环境的影响是考虑到混合量子力学/分子力学（QM/MM）的方法。 开发后，开发的方法将用于研究π-堆叠的核碱基中的光物理和光化学事件。这项工作有助于我们了解DNA如何与紫外线辐射相互作用。光引发的过程，这项工作的主要重点，在光合作用，视觉，光化学损伤和DNA修复中发挥重要作用。Matsika的研究对于研究生物系统中的光引发过程非常有用。 该方法将在公开可用的计算软件中实现。 来自物理科学和本科生中代表性不足的群体的学生是PI研究团队不可或缺的一部分。

Spiridoula Matsika of Temple University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Chemistry division to develop and use theoretical models to understand photo-initiated phenomena in biological systems. Matsika and her research group develop efficient quantum chemical methods for excited states and conical intersections, which are essential in studying photo-initiated processes. The proposed methods enhance the efficiency of multireference configuration interaction (MRCI) by using natural orbitals obtained from a high multiplicity state instead of the traditional multi-configurational orbitals. Initial results show that this approach reduces the computational cost significantly compared to traditional MRCI without loss of accuracy. Gradients are also being developed for this method. The effect of the environment is taken into account by a hybrid quantum mechanics/ molecular mechanics (QM/MM) method. When developed, the developed methods will be used to study photophysical and photochemical events in pi-stacked nucleobases. This work contributes to our understanding of how DNA interacts with UV radiation. Photo-initiated processes, a primary focus of this work, play an important role in photosynthesis, vision, and photochemical damage and repair in DNA. Matsika's research is very useful in studying photo-initiated processes in biological systems. The methodology will be implemented in publicly available computational software. Students from groups that are under-represented in the physical sciences and undergraduate students are an integral part of the PI's research team.