Excitation and Ionization in Atomic Collision Processes -- General Theory and Accurate Numerical Calculations

该项目研究光（主要是激光）和带电粒子（主要是电子）与原子、离子和小分子的相互作用。这些结果对于理解基本的碰撞动力学具有重要意义，也满足了对精确的原子数据进行恒星、等离子体、激光和行星大气物理建模的迫切实际需要。该项目的短脉冲强激光部分处理数值时空网格上时变薛定谔方程的精确解。随着当前计算资源的快速发展，这种针对现实而非理想化模型系统的研究直到最近几年才成为可能。这项工作对于亚微观反应的成像和最终控制的进一步发展非常重要，预计将从物理学延伸到化学并最终产生生物学的广泛影响。世界范围内的许多实验工作都通过本项目得到支持，该项目还将培养一名博士后和一些研究生，使他们对问题有基本的了解，并使用高度复杂的数值技术。大多数数值计算将基于非微扰r矩阵（紧密耦合）方法，以及使用各种基于网格的方法和基函数展开的时变薛定谔方程的直接解。对于用强烈的atto/飞秒激光脉冲进行复杂原子的单电离和双电离，这些方法将以这样一种方式结合起来，即“大问题”的各个部分可以以高效和优化的方式处理。这种策略将扩展到处理涉及内壳层和双原子分子的双电离。特别有趣的将是极具挑战性，但最终必须同时处理核和电子运动。这一问题的表述和随后的数值处理都有很大的困难。重点将放在数值方法的测试和结果的可视化上，这两者都是学生参与的理想选择。

The project studies the interaction of light (mostly lasers) and charged particles (mostly electrons) with atoms, ions, and small molecules. The results are of importance for the understanding of the fundamental collision dynamics, and they also fulfill the urgent practical need for accurate atomic data to model the physics of stars, plasmas, lasers, and planetary atmospheres. The short-pulse intense-laser part of the project deals with accurate solutions of the time-dependent Schroedinger equation on a numerical space-time grid. With the rapid advances currently seen in computational resources, such studies for realistic rather than idealized model systems have only become possible in recent years. This work is important for further developments in imaging and ultimately controlling of submicroscopic reactions, which is expected to have broad impact by reaching out from physics to chemistry and ultimately biology. Many experimental efforts worldwide are supported through the present project, which will also train a post-doctoral associate and a number of research students in the basic understanding of the problem and the use of highly sophisticated numerical techniques.Most of the numerical calculations will be based upon the non-perturbative R-matrix (close-coupling) method, as well as direct solutions of the time-dependent Schroedinger equation using various grid-based approaches and basis-function expansions. For single and double ionization of complex atoms by intense atto/femto-second laser pulses, the methods will be combined in such a way that individual parts of the "big problem" can be treated in highly efficient and optimized ways. This strategy will be extended to the treatment of double ionization involving inner shells as well as diatomic molecules. Of particular interest will be the highly challenging, but ultimately necessary simultaneous treatment of the nuclear and electronic motion. There are major difficulties associated with both the formulation of the problem and the subsequent numerical treatment. Much emphasis will be placed on the testing of numerical methods and the visualization of the results, both of which are ideal for student involvement.