Collision- and laser-induced few-body dynamics in atomic and molecular systems

原子和分子系统中碰撞和激光诱导的少体动力学

• 批准号: RGPIN-2019-06305
• 负责人: Kirchner, Tom
• 金额: $ 2.04万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715198
• 关键词: Collision; laser; induced; few; body

When an atom or a molecule is hit by an energetic ion or is exposed to a strong laser field it may release one or several of its electrons. In the case of a molecular target, this process of ionization may be followed by the break-up of the system into neutral and charged fragments which, similarly to the released electrons, may cause further ionization in surrounding matter. These processes are at the heart of the problem of radiation damage of biological tissue. Their quantitative understanding is the principal objective of this research program. Atoms and molecules follow the laws of quantum physics. When they are exposed to strong fields, either through collisional interactions or by laser illumination, the equations derived from those laws to describe their behaviour are so complex that exact solutions are not feasible. Models, advanced theoretical methods and numerical techniques are then required to make predictions on measurement outcomes or to produce numerical data that can be compared with available measurements to help understand the underlying physics and draw conclusions with regard to possible applications. The work described in this proposal is concerned with the development and execution of such models, methods and techniques. Two avenues of research will be pursued. On a fundamental level, we will use atomic collision problems as test beds for the further development of the so-called time-dependent density functional theory (TDDFT) approach, which is one of only a few theoretical methods available for describing collisional and laser-driven many-electron dynamics on a first-principles basis. We will implement a TDDFT scheme on a higher level of approximation than reported before and carry out numerical calculations for ion-atom collisions to help validate and improve the approach. We will also address an outstanding fundamental TDDFT problem related to the calculation of observable quantities. Our work will advance theory and produce data of interest to experimentalists in the field and to researchers in neighbouring disciplines who are, e.g., analyzing X-ray spectra of astrophysical objects or diagnosing high-temperature plasmas in the context of nuclear fusion experiments. On the more applied side we will study ion collisions from biologically relevant molecules, such as DNA/RNA building blocks, by elaborating on a simplified model description which we have proposed recently. Full first-principles calculations are not feasible for these complicated systems, yet reliable theoretical data would be important for an in-depth understanding of the problem of radiation damage of biological tissue. Our research is aimed at filling this void and producing such data. The results of our model calculations will benefit the field of radiobiology and, potentially, have an impact on clinical applications such as tumour therapy with positively-charged ions, thereby contributing to a more successful treatment of cancer.

当原子或分子被高能离子撞击或暴露于强激光场时，它可能会释放一个或多个电子。在分子目标的情况下，该电离过程之后可能会系统分裂成中性和带电碎片，与释放的电子类似，可能会导致周围物质进一步电离。这些过程是生物组织辐射损伤问题的核心。他们的定量理解是该研究计划的主要目标。 原子和分子遵循量子物理定律。当它们暴露在强场中时，无论是通过碰撞相互作用还是通过激光照射，从这些定律推导出来描述其行为的方程都非常复杂，以至于精确的解决方案是不可行的。然后需要模型、先进的理论方法和数值技术来对测量结果进行预测或生成可以与可用测量进行比较的数值数据，以帮助理解基础物理并就可能的应用得出结论。本提案中描述的工作涉及此类模型、方法和技术的开发和执行。 将采取两条研究途径。在基本层面上，我们将使用原子碰撞问题作为进一步发展所谓的时间相关密度泛函理论（TDDFT）方法的试验台，该方法是可用于描述碰撞和激光的少数理论方法之一。在第一原理的基础上驱动多电子动力学。我们将在比之前报道的更高水平的近似上实现 TDDFT 方案，并对离子原子碰撞进行数值计算，以帮助验证和改进该方法。我们还将解决与可观测量计算相关的一个突出的基本 TDDFT 问题。我们的工作将推进理论发展，并产生该领域的实验人员和邻近学科的研究人员感兴趣的数据，例如分析天体物理物体的 X 射线光谱或在核聚变实验中诊断高温等离子体。 在更应用的方面，我们将通过详细阐述我们最近提出的简化模型描述来研究生物相关分子（例如 DNA/RNA 构建块）的离子碰撞。对于这些复杂的系统来说，完整的第一原理计算是不可行的，但可靠的理论数据对于深入了解生物组织的辐射损伤问题非常重要。我们的研究旨在填补这一空白并产生此类数据。我们的模型计算结果将有利于放射生物学领域，并有可能对临床应用产生影响，例如带正电离子的肿瘤治疗，从而有助于更成功地治疗癌症。