First Principles Simulation Methods for Strong Field Dynamics

强场动力学的第一原理仿真方法

• 批准号: 1954519
• 负责人: Benjamin Levine
• 金额: $ 48万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1954519&HistoricalAwards=false
• 关键词: First; Principles; Simulation; Methods; Strong

Professor Benjamin Levine of Stony Brook University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop molecular-level models of interfacial chemical dynamics. Lasers are used in many fields from advanced manufacturing, to communications, to medicine. Strong laser pulses have arisen as powerful tools for probing electron-nuclear motions in molecules on the short time scales. Though lasers introduce large quantities of energy into molecules in a very short time, the ensuing chemical motions (dynamics) are intricate. Chemical dynamics in strong laser fields are challenging to model with standard approaches, creating a need for more advanced simulation methods. An important motif in laser science is recollision. In this process, the laser field plucks a single electron from the molecule and then drives that electron back into the remaining cation at high energy. The possible outcomes of such recollision processes include scattering, the removal of a second electron, and the emission of a high energy packet of light (photon). Recollision is of fundamental interest and serves as the basis of advanced measurements with attosecond (one quintillionth of a second) time resolution and high spatial resolution. The Levine group will develop first-principles computer simulation methods for modeling recollision. The work will provide the theoretical chemistry community with new theoretical tools for modeling and interpreting strong-field laser experiments. In the process, future scientists, including graduate and undergraduate students, will be trained in chemistry, physics, high-performance computing, and mathematics. Professor Levine plans to organize an international workshop that will facilitate discussion about theoretical methods for modeling chemical problems that challenge theorists. He will continue to work through the Michigan State University local section of the American Chemical Society and its associated student groups (Young Chemists' Committee, Woman in Chemistry) to provide younger chemists with leadership opportunities and mentorship.The Levine group will develop a mixed ansatz, in which the ionization of the full many-electron system is initially treated quantum mechanically via time-dependent configuration interaction (TD-CI), but upon separation from the molecule the ejected electron is treated semiclassically. This novel approach to modeling electron dynamics will be coupled to multiple cloning in dense manifolds of states (MCDMS), a nonadiabatic molecular dynamics scheme capable of accurately and efficiently modeling coupled electron-nuclear dynamics in the continuum of electronic states accessed during ionization. Because this combined TD-CI/MCDMS approach will model the entire ionization/recollision process in full quantum mechanical detail, it avoids the need for common and potentially inaccurate simplifying assumptions about the initial state of the system after ionization. These novel methods will be applied to explicitly model the electron and coupled electron-nuclear dynamics of several small molecules under irradiation by strong laser pulses, enabling both validation of the accuracy of the new simulation methods and elucidation of the intricate electronic motions underlying the experimental observations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

斯托尼·布鲁克大学（Stony Brook University）的本杰明·莱文（Benjamin Levine）教授得到了化学理论，模型和计算方法计划的奖项，以开发界面化学动力学的分子级模型。 从高级制造，通信到医学的许多领域都使用了激光器。强烈的激光脉冲已成为在短时间尺度上探测分子中电子核运动的强大工具。 尽管激光在很短的时间内将大量能量引入分子中，但随后的化学运动（动力学）很复杂。 使用标准方法的强激光场中的化学动力学对于模型的模型具有挑战性，从而需要更高级的仿真方法。 激光科学中的一个重要主题是回忆。 在此过程中，激光场从分子中摘下单个电子，然后将电子驱动到高能以高能的剩余阳离子中。 这种回忆过程的可能结果包括散射，去除第二电子以及发射高能量的光（光子）。 回忆具有基本利益，并作为高级测量的基础，并以attsecond（第二千万千万）时间分辨率和高空间分辨率为基础。 Levine组将开发用于建模回忆的第一原理计算机仿真方法。 这项工作将为理论化学界提供新的理论工具，用于建模和解释强场激光实验。在此过程中，包括毕业生和本科生在内的未来科学家将接受化学，物理，高性能计算和数学的培训。 莱文教授计划组织一个国际研讨会，该研讨会将促进有关建模挑战理论家的化学问题的理论方法的讨论。 他将继续通过密歇根州立大学的美国化学学会及其相关的学生团体（年轻化学家委员会，化学妇女）的地方工作，为年轻的化学家提供领导机会和指导。莱文小组将开发混合的ANSATZ，其中最初是通过机械依赖于时间依赖性的量子来处理整个多电子系统的电离，在该组织中，整个多电子系统的处理（TD-CI）是由分离的，但是电子接受半经验治疗。 这种新颖的对电子动力学建模的方法将与状态密集的多种克隆（MCDMS）耦合，这是一种非绝热分子动力学方案，能够在电离过程中访问的电子状态连续性中的耦合电子 - 核动力学进行准确有效地建模。 由于这种结合的TD-CI/MCDMS方法将以完整的量子机械细节对整个电离/回忆过程进行建模，因此它避免了对电离后对系统初始状态的常见和可能不准确的简化假设的需求。 这些新型方法将应用于明确对通过强激光脉冲在照射下的几个小分子的电子和耦合的电子核动力学建模，从而既可以验证新模拟方法的准确性，又可以通过对实验奖励的综合奖励进行了宣传。基金会的智力优点和更广泛的影响评论标准。