Investigation of Exciton-exciton and Biexcitonic Interactions in Nanomaterials using Explicitly- correlated Quasiparticle Kernel Method

在化学系化学理论、模型和计算方法(CTMC)计划的支持下，锡拉丘兹大学的Arindam Chakraborty将研究纳米材料中一类特定的量子分子相互作用，特别是激子-激子和双激子状态。查克拉博蒂博士和他的团队将使用一种新的方法来降低描述这些相互作用的计算成本，他们将研究支配这些光与物质相互作用的基本过程，以及在纳米材料中产生的激发态。在太阳能转换和存储、量子计算和量子信息处理、高速纳米电子学和超小型明亮光源(如纳米激光)的发展等领域，这些奇异的激发态是已知的关键技术进步的领跑者。要实现这些纳米材料的全部潜力，需要有能力明智地控制纳米粒子的形状、大小和化学功能化，以获得适合这些应用的所需的、精确的化学和物理性能。查克拉博蒂和他的团队正在进行的第一个基于原理的量子化学计算旨在达到这种预测能力和控制水平。这些研究活动将促进科学、技术、工程和数学(STEM)方面的劳动力发展，并在基于云的科学计算、大规模数据的管理和管理以及计算机辅助发现新纳米材料方面对本科生和研究生进行培训。Chakraborty小组目前正在开发的实空间显式相关准粒子核方法旨在解决与大纳米粒子研究相关的高计算量问题。具体地说，基态电子结构计算将使用以原子为中心的赝势进行，电子激发态将使用具有有效电子-空穴哈密顿量的准粒子表示来描述。通过采用实空间形式和使用显式关联的频率相关的电子-空穴相互作用核算符，计算中考虑了多体量子力学关联效应。该方法用于回答亮激子和暗激子之间的耦合问题，以及形状各向异性、尺寸分布、激发态寿命和温度对双激子稳定性的影响。这些计算研究的结果可能会为设计提供参考，并使新材料的发现成为可能，并有助于绘制该领域后续探索性研究的路线。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 (CTMC) Program in the Division of Chemistry, Arindam Chakraborty of Syracuse University will investigate a specific class of quantum molecular interactions in nanomaterials, specifically exciton-exciton and bi-excitonic states. Using a new methodology to reduce the computational costs for charactering these interactions, Dr. Chakraborty and his group will study the fundamental processes governing these light-matter interactions as well as the resulting excited states generated in nanomaterials. These exotic excited states are known frontrunners for critically important technological advances in areas such as solar energy conversion and storage, quantum computing and quantum information processing, and the development of high-speed nano-electronics, and of ultra-small bright light sources such as nano-lasers. Realization of the full potential of these nanomaterials requires the ability to judiciously control the shape, size, and chemical functionalization of nanoparticles in order to achieve desired, precise chemical and physical properties appropriate for these applications. The first principle-based quantum chemical calculations that Chakraborty and his team are conducting are aimed at reaching this level of predictive power and control. These research activities will foster workforce development in science, technology, engineering and mathematics (STEM) and in the training of undergraduate and graduate students in cloud-based scientific computing, curation and management of large-scale data, and in the computer-assisted discovery of novel nanomaterials.The real-space explicitly-correlated quasiparticle kernel approach currently being developed in the Chakraborty group aims to addresse the prohibitively high computational effort associated with the study of large nanoparticles. Specifically, ground electronic structure calculations will be performed using atom-centered pseudo-potentials and electronically excited states will be described utilizing a quasi-particle representation with an effective electron-hole Hamiltonian. Many-body quantum mechanical correlation effects are included in the calculations by employing a real-space formalism and using an explicitly correlated frequency-dependent electron-hole interaction kernel operator. The method developed is being used to answer questions about coupling between bright and dark excitonic states, as well as effects of shape anisotropy, size distribution, lifetime of excited states, and temperature of bi-exciton stability. The findings of these computational studies will likely inform the design and enable the discovery of novel materials and help to chart the course for follow-on exploratory research in the field.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.