Non-Adiabatic Effects in Ultracold Chemistry

能够根据需要精确地制备反应物和控制产物是化学中一个长期珍视的目标。由于近年来在冷却和捕获分子以及在接近绝对零度的温度下控制它们的相互作用方面取得的进展，这一目标正变得越来越有可能实现。化学反应如何在接近绝对零度的碰撞能量下进行这一根本问题，现在可以从实验和理论两个方面进行探索。这种对原子和分子的受控操纵是当前量子技术研究的组成部分，包括量子信息处理和量子计算。这一领域的分子碰撞的理论研究面临着巨大的障碍，因为当所有相关的量子态和外场效应都包括在内时，计算变得难以处理。该NSF奖的目标是开发和实施新的方法来研究超冷化学反应，并对反应物和产品进行完全量子态解析。这项研究可能会产生新的计算程序，能够描述超低温下的化学反应。这项研究跨越了化学、物理和天体物理等不同领域的学科界限，培养了一支高技能的科学和工程队伍。化学的一个最终目标是完全控制反应物和产物的量子态，并具有高选择性和专一性。量子态分辨率既适用于分子的内态，也适用于碰撞过程中涉及的角动量分波。对于大多数分子系统来说，限制部分波需要将碰撞能量降低到开尔文或更低。即使在这种情况下，电子的非绝热和几何相效应在控制化学反应的结果方面也发挥着重要作用。然而，在超冷的制度下，这样的过程在很大程度上仍然没有得到探索。NSF奖的主要目标是开发新的方法和计算机代码来研究低温和超低温下化学反应中的电子非绝热效应。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。

The ability to prepare reactants and control products on demand with quantum state precision is a long cherished goal in chemistry. This goal is increasingly becoming achievable thanks to the progress in recent years in cooling and trapping molecules and controlled manipulation of their interactions at temperatures close to absolute zero. The fundamental question of how chemical reactions proceed at a collision energy close to absolute zero can now be explored both by experiment and theory. Such controlled manipulation of atoms and molecules is an integral part of current research in quantum technologies, including quantum information processing and quantum computing. Theoretical studies of molecular encounters in this area face significant obstacles as computations become intractable when all relevant quantum states and external field effects are included. The goal of this NSF award is to develop and implement new methodologies to study ultracold chemical reactions with full quantum state resolution of both reactants and products. The research may lead to new computational programs capable of describing chemical reactions at ultracold temperatures. The research crosses disciplinary boundaries in diverse areas of chemistry, physics, and astrophysics and develops a highly skilled science and engineering workforce. An ultimate goal in chemistry is the complete control of quantum states of both reactants and products with high selectivity and specificity. The quantum state resolution applies both to the internal states of the molecules and the angular momentum partial waves involved in the collision process. Restricting partial waves requires reducing the collision energy to a kelvin or below for most molecular systems. Even in this regime, electronically non-adiabatic and geometric phase effects play an important role in governing the outcome of a chemical reaction. However, such processes remain largely unexplored in the utracold regime. The main goal of this NSF Award is to develop new methodologies and computer codes to study electronically non-adiabatic effects in chemical reactions at cold and ultracold temperatures.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.