Collision-induced few-body dynamics of atomic and molecular systems

碰撞引起的原子和分子系统的少体动力学

• 批准号: RGPIN-2014-03611
• 负责人: Kirchner, Tom
• 金额: $ 2.26万
• 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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633134
• 关键词: Collision; induced; few; body; dynamics

Atoms and molecules are objects of the quantum world. Given that the basic laws of quantum mechanics have been known since the 1920s, one might think that atomic and molecular structure and dynamics are well understood by now and can be calculated, using those laws, to any desired level of accuracy. This is not the case. When it comes to dynamics, exact solutions of the known equations are not feasible, except for the simplest situations, and they will not be feasible for some time to come despite the ever-increasing availability of computational resources. At the heart of the matter lies the complexity of the quantum-mechanical few-body problem, and on a fundamental level, it is the interest in this problem that drives this research program. We will study quantal few-body dynamics by looking into collisions of ions with atoms and molecules and solving simplified versions of the fundamental equations that govern the collisional interactions. These simplified equations are still far to complex to be solved in pen and paper form. Accordingly, we will develop algorithms and computer programs to obtain numerical solutions. Comparing them with experimental data will shed light on the quantum dynamics at play and on the usefulness and the limitations of our methods, thereby advancing our understanding of the quantum-mechanical few-body problem. Our studies will also benefit the experimentalists working in this area. They will assist them in interpreting their data and guide them in the design of future experiments. For example, recent ionization measurements of lithium atoms have raised the question whether certain processes which involve two of the three lithium electrons contribute to the measured spectra. We plan to study the role and the nature of these processes. One question our calculations will address is whether they are dominated by independent interactions of the impinging ion with each electron, or if the interaction between the electrons is important as well. The latter interaction is associated with so-called electron-correlation effects, which play a central role in many atomic, molecular and condensed-matter systems and give rise to such interesting phenomena as superconductivity.Our work will also have significant applications. A major goal of this research program is to push our methods to make them applicable to collisions involving organic molecules. This will be relevant for the field of radiobiology. When biological tissue is irradiated by protons or heavy ions, electrons are set free and the ionized molecules may break apart. In tumour radiation therapy this contributes to the desired destruction of the tumour and to the undesired destruction of the surrounding tissue. Understanding the problem of radiation damage on a fundamental level requires the detailed analysis of the underlying collision processes. This is what our research is concerned with. In the long term it will benefit the complex field of damage to large molecules such as DNA bases and will potentially have some societal impact in that its outcomes may contribute to a more successful treatment of cancer.

原子和分子是量子世界的物体。鉴于量子力学的基本定律自 20 世纪 20 年代以来就为人所知，人们可能会认为原子和分子的结构和动力学现在已经被很好地理解，并且可以使用这些定律进行计算，达到任何所需的精度水平。事实并非如此。在动力学方面，除了最简单的情况外，已知方程的精确解是不可行的，并且尽管计算资源的可用性不断增加，但在未来一段时间内它们也不可行。问题的核心在于量子力学少体问题的复杂性，从根本上讲，正是对这个问题的兴趣推动了这项研究计划。我们将通过研究离子与原子和分子的碰撞并求解控制碰撞相互作用的基本方程的简化版本来研究量子少体动力学。这些简化的方程仍然过于复杂，无法以笔和纸的形式求解。因此，我们将开发算法和计算机程序以获得数值解。将它们与实验数据进行比较将揭示起作用的量子动力学以及我们方法的有用性和局限性，从而增进我们对量子力学少体问题的理解。我们的研究也将使从事该领域工作的实验人员受益。他们将协助他们解释数据并指导他们设计未来的实验。例如，最近锂原子的电离测量提出了这样的问题：涉及三个锂电子中的两个的某些过程是否对测量的光谱有贡献。我们计划研究这些过程的作用和性质。我们的计算将解决的一个问题是它们是否由撞击离子与每个电子的独立相互作用主导，或者电子之间的相互作用是否也很重要。后一种相互作用与所谓的电子相关效应有关，电子相关效应在许多原子、分子和凝聚态物质系统中发挥着核心作用，并引起超导等有趣的现象。我们的工作也将具有重要的应用。该研究计划的一个主要目标是推动我们的方法使其适用于涉及有机分子的碰撞。这将与放射生物学领域相关。当生物组织受到质子或重离子照射时，电子被释放，电离分子可能会分裂。在肿瘤放射治疗中，这有助于对肿瘤的预期破坏和对周围组织的不希望的破坏。从根本上理解辐射损伤问题需要对潜在的碰撞过程进行详细分析。这就是我们的研究所关心的。从长远来看，它将有利于 DNA 碱基等大分子损伤的复杂领域，并可能产生一些社会影响，因为其结果可能有助于更成功地治疗癌症。