Predicting Excitation Energies in Warm Dense Matter

T. Q. Thelen, D. A. Rehn, C. J. Fontes, C. E. Starrett

Published 2024-03-28Version 1

In a dense plasma environment, the energy levels of an ion shift relative to the isolated ion values. This shift is reflected in the optical spectrum of the plasma and can be measured in, for example, emission experiments. In this work, we use a recently developed method of modeling electronic states in warm dense matter to predict these level energies. In this model, excited state energies are calculated directly by enforcing constrained one-electron occupation factors, thus allowing the calculation of specific transition and ionization energies. This model includes plasma effects self-consistently, so the effect of continuum lowering is included in an ab-initio sense. We use the model to calculate the K-edge and K-alpha energies of solid density magnesium, aluminum, and silicon over a range of temperatures, finding close agreement with experimental results. We also calculate the ionization potential depression (IPD) to compare to widely used models, and investigate the effects of temperature on the lowering of the continuum.