New Coupled-cluster Methods for Linear and Non-linear Valence and Core-level Spectroscopy in Gas and Condensed Phase

南加州大学的安娜Krylov得到了化学系化学理论、模型和计算方法项目的支持，以开发新的理论方法、计算机算法和软件来描述分子和光在新体系（高能量、高强度等）中的相互作用。利用光来询问物质是光谱学的基础，它为解开化学反应机制、材料和生物物体的结构和内在特性提供了最强大的工具。使用高能（X射线）和高强度辐射开辟了新的令人兴奋的机会，这推动了全球数十亿先进光源设施的发展。这些设施中光束质量的最新进展极大地扩展了X射线的可能应用，导致技术的扩散，包括在时间分辨和非线性制度中操作的技术。这些新技术有望大大扩展我们询问分子结构和动力学的能力，但只有当实验通过精确的理论工具来模拟这些现象时，才能实现它们的全部潜力。尽管付出了巨大的努力，但该理论仍然落后于实验能力，为最大限度地发挥数十亿先进光源设施的科学影响创造了瓶颈。Krylov将通过开发新的电子结构方法来模拟气相和凝聚相中的线性和非线性核心水平光谱来弥合这一差距。该研究计划包括培训和指导研究生和博士后在学术界和工业界的职业生涯，以及对研究基础设施的贡献。Krylov将利用芯价分离（CVS）和阻尼响应理论，进一步将高可靠性的耦合团簇（CC）和运动方程CC（EOM-CC）方法扩展到芯能级电离和激发态的领域（或复极化传播器，CPP）方法。具体来说，她将进一步开发用于E2 PA（纠缠2 PA）、PECD（光电子圆二色性）、MCD（磁CD）和电子SFG（和频产生）光谱建模的理论框架和高效计算机代码。她的目标是为UV-vis（价态跃迁）和X射线（核能级跃迁）领域开发一个统一的理论框架。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Anna Krylov of the University of Southern California is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop new theoretical approaches, computer algorithms, and software to describe interaction of molecules and light in new regimes (high energy, high intensities, etc). Using light to interrogate matter is the basis of spectroscopy, which provides the most powerful set of tools for unraveling mechanisms of chemical reactions, structures and intrinsic properties of materials and biological objects. Using high-energy (X-rays) and high-intensity radiation opens new exciting opportunities, which motivate the worldwide development of multi-billion facilities for advanced light sources. Recent advances in beam quality in these facilities greatly expanded possible applications of X-rays, giving rise to a proliferation of techniques including those operating in time-resolved and non-linear regimes. These novel techniques promise to greatly expand our ability to interrogate molecular structure and dynamics, but their full potential can only be realized when experiment is augmented by accurate theoretical tools for modeling these phenomena. Despite significant efforts, the theory is still lagging behind the experimental capabilities, creating a bottleneck for maximizing the scientific impact of multi-billion advanced light source facilities. Krylov will bridge this gap by developing novel electronic structure methods for modeling linear and non-linear core-level spectroscopies in the gas and condensed phases. The research plans include training and mentoring of graduate students and postdocs for careers in academia and industry as well as contributions to the research infrastructure.Capitalizing on her previous work, Krylov will further extend highly reliable coupled-cluster (CC) and equation-of-motion CC (EOM-CC) methods to the domain of core-level ionized and excited states by exploiting core-valence separation (CVS) and damped response theory (or complex polarization propagator, CPP) approaches. Specifically, she will further develop theoretical framework and efficient computer codes for modeling E2PA (entangled 2PA), PECD (photoelectron circular dichroism), MCD (magnetic CD), and electronic SFG (sum-frequency generation) spectra. She aims to develop a uniform theoretical framework for both UV–vis (valence transitions) and X-ray (core-level transitions) domains. Continuing close collaborations with experimentalists guides and calibrate the developments, as well as helps to design new experiments and interpret the experimental results.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.