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Quantum dynamical studies of molecule-doped clusters of rare-gas atoms and hydrogen molecules.

机译：稀有气体原子和氢分子的分子掺杂簇的量子动力学研究。

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This dissertation consists of three parts. Part I reports the Diffusion Monte Carlo (DMC) calculations of the intermolecular vibrational ground states of ArnHF clusters, on the best available pairwise additive potential energy surfaces (PESs) for n = 1--12, and on the high-quality non-additive PESs for n = 1--7 . The intermolecular degrees of freedom of the clusters are treated in full dimensionality. The calculations yield ground state energies, probability distributions of intermolecular coordinates and HF vibrational frequency shifts. The calculated frequency shifts, especially those obtained from the non-additive PESs, show excellent agreement with the available spectroscopic data and provide reliable predictions for future experimental studies.; Part II investigates the quantum solvation of the HF molecule by para-hydrogen molecules. The minimum-energy structures determined for n = 1--12 have all the H2 molecules in the first solvent shell. The first solvent shell closes at n = 12, resulting in an icosahedral solvent cage. The zero-point energy of (p-H2)nHF clusters calculated by DMC is unusually large relative to the potential well depth, making the solvent cage exceptionally fluxional. However, the characteristic features of the static minimum-energy cluster geometries are remarkably preserved and clearly recognizable from the pattern of the modulated H2 density around the HE The rigidity of the solvent clusters displays an interesting size dependence, reaching its maximum for n = 12, where the first solvent shell closes. The anisotropy of the solvent, very pronounced for small clusters, decreases rapidly with increasing n, so that for n ∼ 8--9 the solvent environment is practically isotropic.; Part III deals with the microscopic process where a small number of He atoms solvates the HCl dimer. The size evolution of the equilibrium cluster structures and of the highly quantum solvation dynamics are investigated using DMC. The results reveal that the first six helium atoms are delocalized within the equatorial ring centered in the middle of, and perpendicular to, the line connecting the centers of mass of the two HCl monomers. As more helium atoms are added, the helium density starts to spread beyond the central region of the dimer. The solvation effects on the interchange-tunneling dynamics of the HCl dimer are also discussed.
机译：本文共分三个部分。第一部分报告了ArnHF团簇的分子间振动基态的扩散蒙特卡罗（DMC）计算，在n = 1--12的最佳成对可加成对势能面（PESs）上以及在高质量非可积层上n = 1--7的PES。簇的分子间自由度以完整维度进行处理。计算得出基态能量，分子间坐标的概率分布和HF振动频率偏移。计算出的频移，特别是从非加性PES获得的频移，与可用的光谱数据表现出极好的一致性，并为未来的实验研究提供了可靠的预测。第二部分研究了对氢分子对HF分子的量子溶剂化作用。为n = 1--12确定的最小能级结构在第一溶剂壳中具有所有H2分子。第一个溶剂壳在n = 12时关闭，从而形成了二十面体溶剂笼。 DMC计算的（p-H2）nHF团簇的零点能量相对于潜在的井深而言异常大，这使得溶剂笼具有极高的通量。但是，静态最小能量簇几何结构的特征得到了显着保留，并且可以从HE周围的H2调制密度模式中清楚地看出。溶剂簇的刚性表现出令人感兴趣的尺寸依赖性，在n = 12时达到最大值。第一个溶剂壳关闭的位置。溶剂的各向异性对于小团簇非常明显，随n的增加而迅速降低，因此对于n〜8--9而言，溶剂环境实际上是各向同性的。第三部分涉及微观过程，其中少量He原子将HCl二聚体溶剂化。使用DMC研究了平衡簇结构的尺寸演化和高量子溶剂化动力学。结果表明，前六个氦原子在赤道环内以与两个HCl单体的质心连接的线为中心并垂直于该赤道环而离域。随着添加更多的氦原子，氦气密度开​​始扩散到二聚体的中心区域之外。还讨论了溶剂化对HCl二聚体交换隧穿动力学的影响。

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