Cloudy in the microcalorimeter era: improved energies for K$α$ transitions

Abstract: X-ray missions with microcalorimeter technology will resolve spectral features with unprecedented detail. In this work, we improve the H-like K$\alpha$ energies for elements between 6 $\leq Z \leq$ 30 for the release version of the spectral simulation code Cloudy to match laboratory energies. We update the ionization potential ($I_{\rm ion}$) for these elements and add a fourth-order polynomial to the level energy difference. This brings the release version of Cloudy into a near-perfect agreement with NIST. The updated energies are $\sim$ 15-4000 times more precise than that of the current release version of Cloudy (C17.02). These new changes will be a part of the next update to the release version, C17.03.