RUI: Time-independent excited state methods for computational screening of photoactive materials

西华盛顿大学的蒂姆·科瓦尔奇克获得了化学系化学理论、模型和计算方法项目的支持，开发了快速预测有机材料可见光吸收、能量转换和发射能力的模拟。在这些材料中，将光能重新定向为电子流，构成了新兴技术的基础，包括柔性太阳能电池、低毒流动电池，以及用于治疗某些癌症的非侵入性光疗法。该奖项支持的研究填补了现有方法中的一个关键空白，即能够根据有机材料的光活性进行快速计算筛选。科瓦尔奇克指导一个以本科生为主的学生研究团队开发和应用这些模拟，以了解光吸收材料在隔离和复杂分子环境中的行为。这些快速筛选模拟与高精度建模相结合，以揭示专业有机染料如何利用光中的能量来产生在光动力癌症治疗中摧毁病变组织的活性氧物种的细节。科瓦尔奇克正在将该奖项中开发的模拟演示与本科生主导的与WWU能源研究所合作的能源素养推广计划联系起来。科瓦尔奇克及其同事正在通过在密度泛函紧束缚(DFTB)形式主义中开发、基准评估和应用与时间无关的激发态方法，为光活性材料筛选寻求快速模拟策略。这项研究试图将新兴的与时间无关的DFTB(TI-DFTB)方法转变为一种实用的、计算高效的策略，用于筛选光活性材料以及凝聚相中的多尺度激发态模拟。在该奖项中开发的TI-DFTB分子动力学模拟能够对激发态势能表面进行有效的构象采样，并对分子环境进行自洽的量子力学处理。从TI-DFTB激发态模拟中提取了简单的化学描述符来表征一系列有机生色团对单线态氧的光敏化作用。该奖项支持在一个以本科生为主的机构对不同的本科生和硕士研究生进行培训和指导。

Tim Kowalczyk of Western Washington University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop simulations that rapidly predict the visible-light absorption, energy conversion, and emission capabilities of organic materials. In these materials, the redirection of light energy into a flow of electrons forms the basis of emerging technologies including flexible solar cells, low-toxicity flow batteries, and noninvasive light-based therapies for the treatment of certain cancers. The research supported by this award fills a critical gap in existing methodology to enable fast computational screening of organic materials according to their photoactivity. Kowalczyk mentors a predominantly undergraduate team of student researchers in the development and application of these simulations to understand the behavior of light-absorbing materials both in isolation and in complex molecular environments. These rapid screening simulations are paired with high-accuracy modeling to uncover the details of how specialized organic dyes use the energy in light to produce the reactive oxygen species that destroy diseased tissue in photodynamic cancer therapy. Kowalczyk is linking demonstrations of simulations developed in this award to a program of undergraduate student-led energy literacy outreach in conjunction with WWU's Institute for Energy Studies.Kowalczyk and coworkers are pursuing rapid simulation strategies for photoactive materials screening through the development, benchmarking assessment, and application of time-independent excited state methods within the density-functional tight-binding (DFTB) formalism. This research seeks to transform the nascent time-independent DFTB (TI-DFTB) approach into a practical, computationally efficient strategy for photoactive materials screening as well as for multi-scale excited-state simulations in condensed phases. The TI-DFTB molecular dynamics simulations developed in this award enable efficient conformational sampling on excited-state potential energy surfaces with a self-consistent, quantum mechanical treatment of the molecular environment. Simple chemical descriptors are extracted from TI-DFTB excited-state simulations to characterize the photosensitization of singlet oxygen by a range of organic chromophores. This award supports the training and mentoring of a diverse group of undergraduate and masters-level research students at a primarily undergraduate institution.