Molecules in Quantum Clusters: Structural and Dynamical Probes

该研究项目由NSF理论和计算科学基金会支持。 化学计划，是一个研究氢和氦中的探针分子 集群 团簇的低激发声子态和团簇的相互作用 这些具有探针分子的振转态的状态将被 用量子蒙特卡罗理论来处理 计算数量包括 红外和拉曼光谱中的寿命展宽、位移和分裂 探针分子如六氟化硫或双原子碘。 通过 比较理论与实验测量，主机主机和 主体-杂质耦合可以被确定并用于研究其他能量 量子流体中的耗散过程 第二个主要组成部分 该项目将高能（1 keV）电子散射从 团簇研究电离和弹性散射截面。 长期以来，人们一直知道，由非常多的分子组成的液体（量子液体）， 轻原子或轻分子，尤指氦原子或氢 分子，表现出不寻常的性质，如超流性。 的 该项目的主要目标是测试数学和理论 这些现象的理论方法，通过实验计算 含探针小量子团簇的可及光谱效应 分子。这些基本知识的最直接应用 是空间实验室超流团实验的理论， 以及改进的低温火箭燃料的开发。

This research project, supported by the NSF Theoretical and Computational Chemistry Program, is a study of probe molecules in hydrogen and helium clusters. Low lying phonon states of the cluster and the interaction of these states with rovibrational states of a probe molecule will be treated by quantum Monte Carlo theory. Computed quantities include lifetime broadening, shifts and splittings in infrared and Raman spectra of probe molecules such as sulfurhexafluoride or diatomic iodine. By comparing theory with experimental measurements, the host-host and host-impurity couplings can be determined and used to study other energy dissipation processes in quantum fluids. A second major component of this project treats high energy (1 keV) electron scattering from clusters to study ionization and elastic scattering cross sections. It has long been known that liquids (quantum liquids) composed of very light atoms or molecules, particularly helium atoms or hydrogen molecules, exhibit unusual properties such as superfluidity. The principal goal of this project is to test mathematical and theoretical methods in the theory of these phenomena by computing experimentally accessible spectral effects on small quantum clusters containing probe molecules. The most immediate application of this fundamental knowledge is to the theory of spacelab experiments involving superfluid clusters, and to the development of improved cryogenic rocket fuels.