The Development of Semiclassical Methods for the Evaluation of Vibrational Energy Relaxation Rates in Condensed Media

凝聚态介质中振动能量弛豫率评估半经典方法的发展

• 批准号: 9422786
• 负责人: Michael Herman
• 金额: $ 22.2万
• 依托单位: Tulane University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-03-01 至 1998-08-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9422786&HistoricalAwards=false
• 关键词: Development; Semiclassical; Methods; Evaluation; Vibrational

Michael Herman, Tulane University, is supported by a grant from the Theoretical and Computational Chemistry Program to continue his theoretical work on the development of semiclassical methods for the evaluation of vibrational relaxation rates in condensed media. The goal of this work is the development of well tested, accurate methods that are sufficiently flexible so as to allow for the evaluation of the vibrational energy relaxation in a broad range of physical systems. The strategies for the development of these methods employ a quantum mechanical description of the vibrational motion of the molecules. Semiclassical techniques are employed to describe the time evolution of the nonvibrational degrees of freedom in the system. These methods allow for the coupling of the evolution of the nonvibrational degrees of freedom to the quantum vibrational transitions, while retaining much of the computational advantage of a classical mechanical description. The rate at which molecules gain and lose vibrational energy influences reaction kinetics, energy transport, the interpretation of spectroscopic experiments and many other processes occurring in liquids, dense gases and solids. The theoretical description of this problem, in a manner that leads to quantitative predictions, requires that the vibrations be treated quantum mechanically. The evaluation of transition rates between quantum states of the molecule in a condensed phase system is an important and challenging theoretical problem, requiring the coupling of quantum techniques with procedures for averaging over the multitude of configurations available to the condensed phase system.

杜兰大学（Tulane University）的迈克尔·赫尔曼（Michael Herman）得到了理论和计算化学计划的赠款的支持，旨在继续他关于开发半经典方法的理论工作，以评估浓缩媒体中的振动放松率。 这项工作的目的是开发经过良好测试，准确的方法，这些方法足够灵活，以便在广泛的物理系统中评估振动能量放松。 这些方法开发的策略采用了分子振动运动的量子机械描述。 使用半经典技术来描述系统中非振动自由度的时间演变。 这些方法允许将非振动自由度的演变耦合到量子振动过渡，同时保留了经典机械描述的许多计算优势。 分子增益和失去振动能的速率会影响反应动力学，能量传输，光谱实验的解释以及许多其他过程发生在液体，致密气体和固体中。 该问题的理论描述以导致定量预测的方式，要求将振动机械地处理。 在凝结相系统中分子量子状态之间的过渡速率的评估是一个重要且具有挑战性的理论问题，需要将量子技术与量子系统平均的程序耦合，以平均凝结相位系统可用的多种配置。