# Comment on "Energy levels and radiative rates for Ne-like ions from Cu to Ga" by N.~Singh and S.~Aggarwal [Pramana -- J. Phys. 89 (2017) 79]

## TL;DR

This paper critiques a recent study on energy levels of Ne-like ions, revealing significant discrepancies between reported results from different atomic structure codes and demonstrating errors in the original FAC calculations.

## Contribution

The authors identify and correct inaccuracies in previously published atomic data for Ne-like ions using their own calculations with the same code.

## Key findings

- Discrepancies up to 1.5 Ryd between two sets of energies.
- FAC calculations in the original paper contain errors.
- Highlighted anomalies in the tabulated results.

## Abstract

Recently, N.~Singh and S.~Aggarwal [Pramana -- J. Phys. 89 (2017) 79] have reported energies and lifetimes for 127 levels of three Ne-like ions, namely Cu~XX, Zn~XXI and Ga~XXII. For the calculations they have adopted two independent atomic structure codes, i.e. GRASP and FAC, and have concluded that both codes give comparable energies. However, we find that the differences between the two sets of energies are up to 1.5~Ryd (over 1.6$\times$10$^5$ wavenumbers) for many levels, and for all three ions. In the absence of other available theoretical or experimental data, it becomes difficult to know which set of energies is more accurate. Through our calculations with the same code we demonstrate that their listings from the FAC calculations are incorrect. A few more anomalies noted in their tabulated results are also highlighted.