Quantum Theories of Atomic and Molecular Interactions and their Applications

由于世界是由原子组成的，因此，科学技术中的大多数重要问题都可以归入理解几个原子或多原子量子系统的范畴，这也就不足为奇了。这既包括生命起源这样的“大问题”，也包括日常化学、生物和医学等更实际的问题。虽然这种原子世界图景是健全和自然的，但它在量子层面上的实施是如此困难，以至于它才刚刚开始。量子化学的蛮力方法和往往过于简化的量子多体理论模型都有关键的局限性，没有明确的解决途径。虽然一些科学家开始将希望寄托在未来的量子计算机上，但单靠计算，即使实现了，也永远不会带来真正的理解，而这一直是科学的象征和抱负。这个项目是一个长期计划的一部分，该计划旨在为量子水平上的世界原子图景开发一个新的理论框架。它从原子和分子物理学的角度出发，基于对原子相互作用的最新和最有效的描述。该理论希望能够系统地理解无法用量子化学方法处理的复杂量子系统，并捕获简化多体模型中缺失的许多基本物理学。提出的框架的基础是一种新的有效的原子相互作用理论，将作为该项目的一部分进行开发。它是更传统的量子亏损理论的实质性推广，以前主要针对单尺度各向同性相互作用势而发展和表述的，到所有类型的电磁相互作用，包括各向异性势和多个长度尺度的势。这是能够定量了解原子-分子和分子-分子相互作用的关键因素之一，这两个因素都是量子复杂性首次出现的地方，也是理解由更多原子和/或分子组成的更复杂量子系统的基础。这一奖项反映了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。

Since the world is made of atoms, it is not surprising that most of the important questions in science and technology can be put under the category of understanding a few-atom or a many-atom quantum system. This includes both the "big questions" such as the origin of life, and the more practical questions such as the everyday chemistry, biology, and medicine. While this atomic picture of the world is sound and natural, its implementation at the quantum level is so difficult that it has barely started. Both the brute-force approach of quantum chemistry and the often-over-simplified models of quantum many-body theory have key limitations with no clear path towards resolution. While some scientists are starting to pin their hopes on a future quantum computer, computation alone, even when realized, never brings the true understanding that has always been the symbol and the aspiration of science. This project is a part of a long-term program that intends to develop a new theoretical framework for the atomic picture of the world at the quantum level. It is from the perspective of atomic and molecular physics and is based on new and most efficient characterization of atomic interactions. The theory hopes to enable systematic understanding of complex quantum systems that are impossible to treat in the quantum chemistry approach and capture much essential physics that has been missing from simplified many-body models.The foundation of the proposed framework is a new effective theory of atomic interactions, to be developed as a part of this project. It is a substantial generalization of the more traditional quantum defect theories, previously developed and formulated mostly for single-scale isotropic interaction potentials, to electromagnetic interactions of all types including anisotropic potentials and potentials with multiple length scales. This is one of the key ingredients that will enable the quantitative understanding of atom-molecule and molecule-molecule interactions, which are both where quantum complexity first emerges and the foundation for the understanding of more complex quantum systems made of more atoms and/or molecules.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.