Semiclassical Methods for the Evolution of Nonequilibrium Systems Undergoing Quantum Transitions

经历量子跃迁的非平衡系统演化的半经典方法

• 批准号: 0203041
• 负责人: Michael Herman
• 金额: $ 31.36万
• 依托单位: Tulane University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0203041&HistoricalAwards=false
• 关键词: Semiclassical; Methods; Evolution; Nonequilibrium; Systems

In this project funded by the Theoretical and Computational Chemistry Program of the Chemistry Division, Herman will develop numerically efficient and accurate semiclassical methods to evaluate quantum transition probabilities and correlation functions in nonequilibrium condensed-phase, gas-phase, and molecular-beam systems. These density-evolution methods require consideration of the full quantum nature of the evolution only for times on the order of the loss of quantum phase coherence. These methods are systematically correctable and provide an estimate of the calculational error at each level of approximation. The procedures will be tested on simple model problems for which exact quantum results can be obtained and then on problems for which experimental data is available. The results of calculations using these methods will also be compared with those obtained using other computational methods.At a time when experimental methods are able to characterize increasingly fast processes, it is imperative to develop theoretical formalisms that are capable of describing such processes. The work proposed here addresses that need. It further promises to provide a framework for analyzing and interpreting ultra-fast nonequilibrium processes in excited-state systems. The planned extension of the methods to systems that are far from equilibrium will allow simulation of new classes of chemical reactions.

在这个由化学系理论和计算化学项目资助的项目中，赫尔曼将开发数值有效和准确的半经典方法来评估非平衡凝聚相，气相和分子束系统中的量子跃迁概率和相关函数。 这些密度演化方法只需要考虑量子相位相干性损失的数量级上的时间演化的全部量子性质。 这些方法是系统可校正的，并提供了在每个近似水平的计算误差的估计。 这些程序将在简单的模型问题上进行测试，这些问题可以得到精确的量子结果，然后在实验数据可用的问题上进行测试。 使用这些方法的计算结果也将与使用其他计算方法获得的结果进行比较。在实验方法能够表征越来越快的过程的时候，必须开发能够描述这种过程的理论形式。 这里提出的工作就是为了满足这一需要。 它进一步承诺提供一个框架，用于分析和解释激发态系统中的超快非平衡过程。 计划将这些方法扩展到远离平衡的系统，将允许模拟新的化学反应类别。