Development of a General, Fully Relativistic, Parallelized B-Spline R-Matrix with Pseudo-States Program for Electron and Photon Interactions with Atoms, Ions, and Molecules

Drake University, Des Moines IA

Investigators

Abstract

The purpose of this project is to further develop a general and effective, fully relativistic computer code for electron and photon interactions with atoms, ions, and molecules using the B-spline R-matrix (BSR) method. This innovative approach has significant advantages over the standard suite of R-matrix codes, mostly developed over the past four decades in Belfast and currently used worldwide. Specifically, the excellent numerical properties of a B-spline basis allow for high computational accuracy, and the ability to employ non-orthogonal sets of term-dependent orbitals allows for compact configuration expansions. During the current funding period, the existing computer code will be fully parallelized, and a new suite of general atomic structure codes will be developed, which directly use the B-spline as an improved interface to the BSR collision codes. Furthermore, a parallelized B-spline code to solve the close-coupling equations in the outer region will be developed, and a pilot version of the BSR program to treat time-dependent processes, such as intense short-pulse XUV laser-atom interactions, will be extended to double ionization and infrared radiation. Finally, the potential use of the BSR method to describe electron and photon interactions with diatomic molecules will be investigated. The broader impact of the project consists of the further development of a highly successful suite of computer programs to calculate accurate atomic data for a wide variety of electron- and photon-driven processes. The production calculations will focus on atomic targets, for which these data are of critical value to model the physics and chemistry of astrophysical and laboratory plasmas, lasers, and planetary atmospheres. This work will support many experimental projects ranging from industrial lighting systems to fundamental research performed at next-generation synchrotrons and free-electron lasers. The results will be presented at international scientific meetings, and the next version of the computer code will be written up and made available to the public. Finally, undergraduate students will be trained through developing and testing individual modules of the package. This includes running the code on massively parallel computing platforms provided through XSEDE resources.