Development of a General and Effective B-spline R-matrix Computer Program for Electron and Photon Collisions with Atoms, Ions, and Molecules

开发通用且有效的 B 样条 R 矩阵计算机程序，用于电子和光子与原子、离子和分子的碰撞

• 批准号: 0555226
• 负责人: Klaus Bartschat
• 金额: $ 29.02万
• 依托单位: Drake University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0555226&HistoricalAwards=false
• 关键词: Development; General; Effective; spline; matrix

Further development of a general and effective program for electron collisions with atoms andions using a B-spline approach with non-orthogonal orbitals will be undertaken. The approach is based upon an extended version of the R-matrix method, in which non-orthogonalorbitals are extensively used for describing both the target states and the scattering functions.The new approach is essentially free of the three major problems that often arise when the most frequently used suite of R-matrix codes, mostly developed over the past three decades in Belfast and currently used world-wide, is applied to truly complex targets such as heavy noble gases or open-shell transition elements. These problems include i) the difficulties in describing all target states of interest for a given calculation to sufficient accuracy, ii) the likely occurrence of unphysical structures, so-called pseudo-resonances, when an attempt is made to address the former problem, and iii) numerical difficulties due to an ill-conditioned orthogonalization procedure and the need to modify the so called Buttle correction.The excellent numerical properties of a B-spline basis used for the description of the continuumstates in the inner region allow for high computational accuracy, while the completeness of the basis will ensure that no Buttle correction to the R-matrix elements is required. With the non-orthogonal orbital technique the target states can be generated from independent calculations, with compact configuration expansions. During the funding period, the following extensions will be undertaken:1) parallelize the code to allow for the treatment of even more challenging problems;2) include a sufficient number of pseudo-states to simulate coupling to the ionization continuum,thereby allowing for accurate results to be generated at intermediate energies;3) use extention 2) above to generate results for ionization processes;4) generate the target orbitals by the relativistic Hartree-Fock method;5) treat charged-particle impact and multi-photon single- and double-ionization;6) treat electron collisions with diatomic molecules.

利用非正交轨道的b样条方法进一步开发电子与原子和离子碰撞的一般有效程序。该方法是基于扩展版的r -矩阵方法，其中非正交轨道广泛用于描述目标状态和散射函数。当最常用的r矩阵代码套件（主要是过去三十年在贝尔法斯特开发的，目前在世界范围内使用）应用于真正复杂的目标，如重惰性气体或开壳跃迁元素时，这种新方法基本上没有经常出现的三个主要问题。这些问题包括i)在给定计算中以足够的精度描述所有感兴趣的目标状态的困难，ii)当试图解决前一个问题时，可能出现非物理结构，即所谓的伪共振，以及iii)由于病态正交化过程和需要修改所谓的巴特尔校正而导致的数值困难。用于描述内区域连续状态的b样条基的优异数值性质允许高计算精度，而基的完整性将确保不需要对r矩阵元素进行巴特尔校正。利用非正交轨道技术，可以通过独立计算生成目标态，其构型展开紧凑。在资助期内，将进行以下扩展：1)并行化代码，以便处理更具挑战性的问题；2)包含足够数量的伪态来模拟与电离连续体的耦合，从而允许在中等能量下产生准确的结果；3)使用上述扩展2)生成电离过程的结果；4)用相对论Hartree-Fock方法生成目标轨道；5)处理带电粒子碰撞和多光子单电离和双电离；6)处理电子与双原子分子的碰撞。