Over the last 25 years, the formalism known as coupled-cluster (CC) theory has emerged as the method of choice for the ab initio calculation of intermolecular interaction potentials. The implementation known as CCSD(T) is often referred to as the gold standard in quantum chemistry. It gives excellent agreement with experimental observations for a variety of energy-transfer processes in molecular collisions, and it is used to calibrate density functional theory. Here, we present measurements of low-energy collisions between NO radicals and H₂ molecules with a resolution that challenges the most sophisticated quantum chemistry calculations at the CCSD(T) level. Using hitherto-unexplored anti-seeding techniques to reduce the collision energy in a crossed-beam inelastic-scattering experiment, a resonance structure near 14 cm⁻¹ is clearly resolved in the state-to-state integral cross-section, and a unique resonance fingerprint is observed in the corresponding differential cross-section. This resonance structure discriminates between two NO–H₂ potentials calculated at the CCSD(T) level and pushes the required accuracy beyond the gold standard.

在过去的25年中，被称为耦合簇（CC）理论的形式主义已经成为分子间相互作用势从头算的一种选择方法。被称为CCSD（T）的实现通常在量子化学中被称为金标准。它与分子碰撞中各种能量转移过程的实验观察结果非常吻合，并用于校准密度泛函理论。在这里，我们介绍了NO自由基与H ₂之间的低能碰撞测量分辨率挑战CCSD（T）级最复杂的量子化学计算的分子。使用迄今未探索的防种子技术来减少横梁非弹性散射实验中的碰撞能量，可在状态到状态的整体横截面中清楚地分辨出14 cm ^-1附近的共振结构，并产生独特的共振在相应的微分横截面中观察到指纹。这种共振结构区分了在CCSD（T）级计算出的两个NO–H ₂电位，并将所需的精度推到了金标准之上。