Computer Simulation of Chemical Dynamics

理论和计算化学计划是支持 韦恩州立大学的威廉·海斯教授在接下来的三年里 年 在这个研究项目中，经典分子动力学模拟 将用于研究个体的微观原子运动 分子和化学反应系统，目的是比较 通过实验和确定关于 分子内动力学、能量传递和化学反应动力学 和动力学。 由于统计理论被广泛用于解释 实验中，将进行统计计算，以比较 分子动力学模拟 选择的具体问题 主要研究内容有：（1）CH_3和H原子与金刚石缔合的动力学 碰撞诱导解离中的能量传递动力学 (CID)和表面诱导解离（SID）; 气相亲核取代反应;（4）直接从头算， 半经验动力学 经典分子动力学预计 为这些研究问题提供准确的结果，并考虑到他们的 复杂性，量子动力学计算将是困难的。 直接 动力学，轨迹通过接口“在飞行中”集成 电子结构理论与分子动力学 仿真。 这是一种前沿的模拟方法， 这与现代计算机的计算能力直接相关。 直接半经验动力学可用于长期研究大系统 时间（例如CID和SID），而从头开始直接动力学可以应用于 到小的系统。 后者的一个例子是 出口通道和能量分配动态的轨迹，因为他们 从一个潜在的能量障碍转移到产品。 最新技术水平 矢量和并行处理计算机体系结构将用于 增强直接动力学模拟。 在本研究项目中，分子建模和模拟用于 研究单个分子的运动和分子碰撞 导致化学反应和能量转移。 分子模拟 方法已经变得足够复杂， 预测性，给出接近定量的结果。 这项研究将 在未来三年内进行的包括应用程序 完善的模拟方法来解释新的实验结果 和测试理论模型，以及更直接的发展， 研究大分子系统的模拟方法。 具体 进行的模拟是：（1）导致金刚石膜的反应 生长;（2）团簇碎裂的质谱实验， 离子与表面碰撞时的碎裂。 后者 已被提议作为肽测序的程序;（3）反应 离子和分子之间的联系;（4）高能量的 分子。

The Theoretical and Computational Chemistry Program is supporting Professor William Hase of Wayne State University for the next three years. In this research project classical molecular dynamics simulations will be used to study the microscopic atomistic motion of individual molecules and of chemical reactive systems, with the goals of comparing with experiment and determining fundamental information about intramolecular dynamics, energy transfer, and chemical reaction dynamics and kinetics. Since statistical theories are widely used to interpret experiment, statistical calculations will be performed to compare with the molecular dynamics simulations. The specific problems chosen for study are: (1) the kinetics of CH3 and H atom association with diamond surfaces; (2) energy transfer dynamics in collision-induced dissociation (CID) and surface-induced dissociation (SID); (3) the dynamics of gas-phase nucleophilic substitution; and (4) direct ab initio and semiempirical dynamics. Classical molecular dynamics is expected to give accurate results for these research problems and, given their complexity, quantum dynamical calculations would be difficult. In direct dynamics, trajectories are integrated `on the fly` by interfacing electronic structure theory directly with the molecular dynamics simulations. This is a frontier approach for performing simulations, which is directly linked to the computational power of modern computers. Direct semiempirical dynamics may be used to study large systems for long times (e.g. CID and SID), while ab initio direct dynamics may be applied to small systems for short times. An example of the latter is the exit-channel and energy partitioning dynamics of trajectories as they move from a potential energy barrier to products. State-of-the art vector and parallel processing computer architecture will be used to enhance the direct dynamics simulations. In this research project molecular modeling and simulation is used to study the motion of individual molecules and of molecular collisions leading to chemical reaction and energy transfer. Molecular simulation methodologies have become sufficiently sophisticated that they are often predictive, giving near-quantitative results. The research to be performed during the upcoming three year period includes applications of well-developed simulation methods to interpret new experimental results and test theoretical models, as well as the development of more direct simulation approaches for studying large molecular systems. The specific simulations to be performed are of: (1) reactions leading to diamond film growth; (2) mass-spectroscopy experiments of cluster fragmentation and fragmentation of ions when they collide with the surfaces. The latter has been proposed as a procedure for sequencing peptides; (3) reactions between ions and molecules; and (4) the fragmentation of highly energized molecules.