AMBiT: A program for high-precision relativistic atomic structure calculations

TL;DR

AMBiT is a high-precision software package that combines relativistic CI+MBPT methods with advanced computational techniques to accurately calculate atomic structures and transitions, especially for complex open-shell systems.

Contribution

The paper introduces AMBiT, a novel software implementing relativistic CI+MBPT with new numerical methods for efficient, high-accuracy atomic structure calculations of complex systems.

Findings

Enables high-accuracy calculations for open-shell systems with many valence electrons.

Employs modern high-performance computing techniques for efficiency.

Provides reliable calculations of energy levels, transition matrix elements, g-factors, and isotope shifts.

Abstract

We present the AMBiT software package for general atomic structure calculations. This software implements particle-hole configuration interaction with many-body perturbation theory (CI+MBPT) for fully relativistic calculations of atomic energy levels, electric- and magnetic-multipole transition matrix elements, g-factors and isotope shifts. New numerical methods and modern high-performance computing techniques employed by this software allow for the calculation of open-shell systems with many valence-electrons ($N > 5$) to a high degree of accuracy and in a highly computationally efficient manner.