pCI: a parallel configuration interaction software package for high-precision atomic structure calculations

TL;DR

pCI is a high-performance software package for atomic structure calculations that integrates configuration interaction with advanced correlation and QED corrections, enabling precise atomic property predictions.

Contribution

It introduces a versatile, parallelized software framework combining CI, MBPT, all-order methods, and QED corrections for high-precision atomic calculations.

Findings

Supports calculations of energy levels, g-factors, and hyperfine constants.

Employs modern HPC techniques for efficient large-scale computations.

Enhances accuracy by including core correlations and QED effects.

Abstract

We introduce the pCI software package for high-precision atomic structure calculations. The standard method of calculation is based on the configuration interaction (CI) method to describe valence correlations, but can be extended to attain better accuracy by including core correlations via many-body perturbation theory (CI+MBPT) or the all-order (CI+all-order) method, as well as QED corrections via QEDMOD. The software package enables calculations of atomic properties, including energy levels, g-factors, hyperfine structure constants, multipole transition matrix elements, polarizabilities, and isotope shifts. It also features modern high-performance computing paradigms, including dynamic memory allocations and large-scale parallelization via the message-passing interface, to optimize and accelerate computations.