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

在化学系化学理论、模型和计算方法课程的支持下，弗吉尼亚理工学院和州立大学的丹尼尔·克劳福德教授将开发能够对分子，特别是手性分子进行计算表征的方法和途径。手性分子显示手性;因此，分子有左手和右手形式，这些形式使平面偏振光波以相反的方向旋转。了解手性分子对制药工业特别重要，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。准确预测手性分子的光学性质是计算化学的一项艰巨任务。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，克劳福德教授和同事们正在努力开发强大而准确的计算技术，这些技术比现有方法耗时更少。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，该研究计划将为研究生和本科生提供量子化学方法的基础理论和发展方面的教育和培训。该项目期间开发的软件将包含在PSI 4中，PSI 4是一种广泛使用的计算化学软件包，可免费提供给社区。Crawford博士是PSI 4的主要开发者之一。在此奖项下，弗吉尼亚理工大学的丹尼尔克劳福德教授和同事将通过补充方法简化耦合团簇理论，奋进推进手光学性质的高精度建模。Crawford小组将扩展他们最近的合作工作，开发一种“图解”随机耦合簇方法，该方法将高精度耦合簇方法（通过四重激发）的内存成本降低了100倍，以利用他们新开发的方法来降低底层相关波函数的维数。此外，在他们证明了引入随时间变化的外部电场会产生比场扰动波函数更大的波函数稀疏性之后，Crawford团队将开发一种局部相关的实时耦合集群方法，该方法旨在利用现有的线性尺度框架。最后，他们将开发和实施振动圆二色光谱使用先进的相关波函数的第一个模拟。这些新模型的开发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标志。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.