CAREER: Quantum-mechanical methods for electronic excited states in complex systems

佛罗里达州立大学的尤金·德普林斯教授受到化学系化学理论、模型和计算方法计划的资助，旨在开发新的理论和计算机算法，以帮助描述复杂分子和材料的电子结构。德普林斯博士和他的团队正在开发一种技术，用一种方法(两电子简化密度矩阵：2-RDM)来描述一个有多个电子的系统，这种方法可以将问题简化为两个电子，而不是更熟悉、更复杂的多电子技术。因为2-RDM方法比多电子波函数更紧凑，所以这些方法可以在复杂系统上进行大量计算，而这是传统方法不可能实现的。正在开发的理论和算法促进了与能量转换、催化和先进储能技术相关的新分子和材料的发现和表征。德普林斯教授还在开发化学物理课程、系列讲座和在线教育内容，目标是在佛罗里达州立大学化学和生物化学系建立化学物理博士轨道。该项目旨在开发一个描述复杂系统中电子激发态的理论和计算框架。在这里，术语络合物指的是两类系统之一：(I)其电子波函数不能用单一电子构型定性地描述的分子(即强相关系统)或(Ii)嵌入极端环境中的分子，例如那些在等离子体纳米粒子附近的分子，在那里强烈的外部电场可以显著扰乱分子的电子密度。对于前一类，人们正在发展频率和时间域方法来从变分双电子约化密度矩阵(2-RDM)驱动的完全活跃空间自洽场计算中提取激发态信息。对于后一类，研究人员和他的团队正在开发在时间域中模拟等离子体-分子相互作用的全量子力学方法。由于等离子体激元是以量子力学的方式建模的，因此这种方法捕捉到了量子力学效应，例如等离子体激元激发之间的纠缠和相干。德普林斯教授将作为这项研究工作的一部分开发的代码放在公共领域的免费或商业电子结构包中。向公众提供这些代码有助于新材料的发现和整个项目开发的数值方法的进步。

Professor Eugene DePrince of Florida State University is funded by the Chemical Theory, Models, and Computational Methods program of the Chemistry Division to develop new theories and computer algorithms to aid in the description of the electronic structure of complex molecules and materials. Dr. DePrince and his group are developing techniques that describe a system with many electrons using an approach (two-electron reduced-density matrix: 2-RDM) that reduces the problem to two electrons, rather than the more familiar and complicated many-electron techniques. Because the 2-RDM approach is more compact than the many-electron wave function, these methods enable large computations on complex systems that are not possible using conventional approaches. The theories and algorithms being developed facilitate the discovery and characterization of novel molecules and materials relevant energy conversion, catalysis, and advanced energy storage technologies. Professor DePrince is also developing Chemical Physics courses, a lecture series, and online educational content with the goal of establishing a Chemical Physics PhD track in the Department of Chemistry and Biochemistry at Florida State University.The project aims to develop a theoretical and computational framework for the description of electronically excited states in complex systems. Here, the term complex refers to systems that fall into one of two categories: (i) molecules whose electronic wave functions cannot be described qualitatively by a single electronic configuration (i.e. strongly correlated systems) or (ii) molecules embedded in extreme environments, such as those in the vicinity of a plasmonic nanoparticle, where intense external electric fields can significantly perturb the electron density for the molecule. For the former category, frequency- and time-domain methods are being developed to extract excited-state information from variational two-electron reduced-density matrix (2-RDM)-driven complete active space self-consistent field computations. For the latter category, the investigator and his group are developing fully-quantum mechanical approaches that simulate plasmon-molecule interactions in the time domain. Because the plasmon is modeled in a quantum-mechanical way, such an approach captures quantum-mechanical effects, such as entanglement and coherences between plasmon excitations. Professor DePrince places the codes developed as part of this research effort in the public domain in either free or commercial electronic structure packages. Making these codes available to the public facilitates the discovery of novel materials and the advancement of the numerical methods developed throughout the project.