The translation-rotation (TR) dynamics and spectroscopy of light molecules, e.g. H , HD, HF, and H O, inside nanoscale cavities such as those of fullerenes and in clathrate hydrates, is dominated by strong nuclear quantum effects (NQEs) to a degree that is without parallel among realistic molecular species. The NQEs include the large TR zero-point energy, quantisation of the translational centre-of-mass motions of the guest molecule, the coupling of various angular momenta in the system, and nuclear spin isomerism. They leave rich and intriguing fingerprints in the inelastic neutron scattering (INS) spectra arising from the transitions between the TR levels of the systems studied. Here we describe the major methodological advances made in the past decade, in both bound-state and scattering calculations that, when combined, have led to the novel and powerful approach for rigorous quantum simulations of the INS spectra a diatomic molecule, homo- and heteronuclear, inside a nanocavity of an arbitrary geometry. As illustrated by several demanding applications, these simulations have been indispensable, and very successful, for the assignment and interpretation of the measured INS spectra. Very surprisingly, this effort has also resulted in the completely unexpected, precedent-setting discovery of the INS selection rule for diatomic molecules in near-spherical nanocavities, overturning the widely accepted view that the INS has no selection rules.

中文翻译：

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富勒烯和笼形水合物纳米腔内的光分子：非弹性中子散射光谱和来自严格量子模拟的意外选择规则

在富勒烯和笼形水合物等纳米级腔内，光分子（例如 H2、HD、HF 和 H2O）的平移-旋转 (TR) 动力学和光谱在一定程度上受强核量子效应 (NQE) 的支配这在现实的分子物种中是无与伦比的。NQE 包括大 TR 零点能量、客体分子平移质心运动的量化、系统中各种角动量的耦合以及核自旋异构。它们在由所研究系统的 TR 能级之间的跃迁产生的非弹性中子散射 (INS) 光谱中留下了丰富而有趣的指纹。在这里，我们描述了过去十年中在束缚态和散射计算方面取得的主要方法学进步，结合起来，已经导致了一种新颖而强大的方法，用于对 INS 光谱进行严格的量子模拟，即在任意几何形状的纳米腔内，同核和异核双原子分子。正如几个要求苛刻的应用所说明的那样，这些模拟对于测量的 INS 光谱的分配和解释来说是必不可少的，而且非常成功。非常令人惊讶的是，这项努力还导致了完全出乎意料的、开创性的发现近球形纳米腔中双原子分子的 INS 选择规则，推翻了广泛接受的认为 INS 没有选择规则的观点。这些模拟对于测量的 INS 光谱的分配和解释来说是必不可少的，而且非常成功。非常令人惊讶的是，这项努力还导致了完全出乎意料的、开创性的发现近球形纳米腔中双原子分子的 INS 选择规则，推翻了广泛接受的认为 INS 没有选择规则的观点。这些模拟对于测量的 INS 光谱的分配和解释来说是必不可少的，而且非常成功。非常令人惊讶的是，这项努力还导致了完全出乎意料的、开创性的发现近球形纳米腔中双原子分子的 INS 选择规则，推翻了广泛接受的认为 INS 没有选择规则的观点。