Reduced-Scaling Coupled Cluster Theory in the Frequency and Time Domains

在化学系化学理论、模型和计算方法项目的支持下，弗吉尼亚理工学院和州立大学的Daniel Crawford教授将开发方法和方法，使分子，特别是手性分子的计算表征成为可能。手性分子显示手性；因此，有左旋和右旋形式的分子，这些形式旋转平面偏振光波在相反的方向。了解手性分子对制药工业尤其重要，因为一种手性形式可能具有很大的药用价值，而另一种形式可能没有价值甚至有毒。对于计算化学来说，准确预测手性分子的光学性质是一项艰巨的任务。虽然简单分子性质的计算机模型已经建立得很好，但手性分子与光的相互作用即使对于最先进的计算方法也提出了独特的挑战。在这个研究项目中，Crawford教授和他的同事们正在努力开发强大而准确的计算技术，这种技术比目前的方法更节省时间。这些计算工具有潜力帮助研究人员更好地理解手性分子结构及其与光的相互作用之间的关系。此外，该研究项目将为研究生和本科生提供量子化学方法基础理论和发展方面的教育和培训。在这个项目中开发的软件将包含在PSI4中，PSI4是一个广泛使用的计算化学包，可以免费提供给社区。Crawford博士是PSI4的主要开发者之一。根据该奖项，弗吉尼亚理工大学的Daniel Crawford教授和他的同事们将通过互补的方法，通过精简耦合簇理论，努力推进热学特性的高精度建模。Crawford小组将扩展他们最近在“图解”随机耦合簇方法开发上的合作工作，该方法展示了高精度耦合簇方法（通过四重激励）解决方案的存储成本降低了一百倍，以利用他们新开发的方法来降低潜在相关波函数的维数。此外，根据他们的演示，引入时间相关的外电场比场扰动波函数产生更大的波函数稀疏性，Crawford团队将开发一种局部相关的实时耦合簇方法，该方法旨在利用现有的线性缩放框架。最后，他们将利用先进的相关波函数开发和实现振动圆二色光谱的首次模拟。这些新模型的发展将涉及与实验学家和理论家的密切合作，这是克劳福德实验室研究的一个特点。该奖项反映了美国国家科学基金会的法定使命，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。

With support from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry, Professor Daniel Crawford of Virginia Polytechnic Institute and State University will develop methods and approaches that enable the computational characterization of molecules, especially chiral molecules. A chiral molecule displays handedness; thus, there are left-handed and right-handed forms of the molecule and these forms rotate plane-polarized light waves in opposite directions. Understanding chiral molecules is especially important to the pharmaceutical industry as one chiral form may be of great medicinal value, while the other form may be of no value or even toxic. The accurate prediction of the optical properties of chiral molecules is a daunting task for computational chemistry. While computer models of simple molecular properties are well established, interactions of chiral molecules with light present unique challenges even for state-of-the-art computational methods. In this research project, Professor Crawford and coworkers are working to develop robust and accurate computational techniques that are less time-intensive than current methods. These computational tools have to potential to help researchers better understand the relationship between chiral molecular structures and their interactions with light. Further, this research program will the provide for the education and training of graduate and undergraduate students in the fundamental theory and development of quantum chemical methods. Software developed during this project will be included in PSI4, a widely used computational chemistry package that is freely available to the community. Dr. Crawford is one of the lead developers of PSI4.Under this award, Professor Daniel Crawford and coworkers at Virginia Tech will endeavor to advance the high-accuracy modeling of chiroptical properties by streamlining coupled cluster theory through complementary approaches. The Crawford group will be extending their recent collaborative work on the development of a "diagrammatic" stochastic coupled cluster approach that exhibits a hundred-fold reduction in the memory costs for the solution of high-accuracy coupled cluster methods (through quadruple excitations) to take advantage of their newly developed methods for reducing the dimensionality of the underlying correlated wave functions. In addition, following their demonstration that the introduction of a time-dependent external electric field yields substantially greater wave function sparsity than that of the field-perturbed wave function, the Crawford team will develop a locally correlated real-time coupled cluster approach that is designed to take advantage of existing linear-scaling frameworks. Finally, they will develop and implement the first simulations of vibrational circular dichroism spectroscopy using advanced correlated wavefunctions. Development of these new models will involve close collaborations with both experimentalists and theorists, a hallmark of studies in the Crawford laboratory.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.