Application of the Variational R-matrix Method for the Dirac Equation to the Be Atom

TL;DR

This paper applies a non-iterative R-matrix method to solve the Dirac equation for the Be atom, providing accurate photoionization cross-section results and revealing new relativistic effects and couplings.

Contribution

It introduces a non-iterative eigenchannel R-matrix approach for the Dirac equation and demonstrates its effectiveness on the Be atom, highlighting new relativistic phenomena.

Findings

Results agree with previous calculations and experiments.

Observed change in Fano line shape of the (2pnd)1P series.

Discovered a new coupling between triplet and singlet series.

Abstract

This paper presents an implementation of the non-iterative eigenchannel R-matrix method for the Dirac equation. It includes a brief introduction, implementation details, and results for the photoionization cross-section of the beryllium atom. Beryllium is a convenient test due to small but significant relativistic effects. The current calculation aligns with other R-matrix calculations and experiments. It observes the change in the Fano line shape of the (2pnd)1P series and, reveals a previously unnoticed coupling between triplet and singlet series observable in the ground state photoionization cross-section.