Molecular Neutron Spectroscopy: Experiment and Ab Initio Methods

在这个由化学部门实验物理化学计划支持的项目中，Hudson将使用非弹性非相干中子散射（IINS）光谱来研究多晶样品中氢原子的低频运动。将进行理论与实验的比较，以检验ab-initio方法的可靠性，方法是根据氢原子运动对特定正态模的贡献来检验它们产生氢原子运动精确特征向量的能力。待研究的分子包括：(a)经验或从头算方法可能失败的分子；(b)振动谱实验分析不明确；(c)以前没有使用光学方法检测到振动；(d)分子表现出很强的分子间相互作用。Hudson建议在英国卢瑟福阿普尔顿实验室（RAL）使用ISIS脉冲中子散裂源。这里提出的研究对于理解凝聚态的各种基本过程至关重要，包括生物分子中能量流动的机制。中子散射光谱技术目前为解决这类问题提供了最直接的方法。由于这个项目的成果，美国可以期望更多的科学家参与中子源的工作。

In this project supported by the Experimental Physical Chemistry Program of the Chemistry Division, Hudson will use inelastic incoherent neutron scattering (IINS) spectroscopy to investigate low frequency motions of hydrogen atoms in polycrystalline samples. Comparisons of theory with experiment will be carried out to test the reliability of ab-initio methods by examining their ability to produce accurate eigenvectors for hydrogen atom motions in terms of the contribution of H-atom motion to particular normal modes. Molecules to be studies include those for which (a) empirical or ab-initio methods are expected to fail; (b) experimental analysis of vibrational spectrum is ambiguous; (c) vibrations have not previously detected using optical methods; and (d) the molecule exhibits strong intermolecular interactions. Hudson proposes to use the ISIS pulsed neutron spallation source at the Rutherford Appleton Lab (RAL) in England.The studies proposed here are crucial to understanding a wide variety of fundamental processes in the condensed phase, including the mechanisms by which energy flows in biological molecules. The technique of neutron scattering spectroscopy currently provides the most straightforward method for addressing such questions. As a result of the outcomes of this project, more scientists in the United States can be expected to become involved in work with neutron sources.