MD-Informed Microfields of HED Plasmas for Line Shape Calculations

Many properties used to study and classify astronomical objects depend upon the opacities of their constituent plasmas. Spectral line shapes are essential for determining the temperature and density of observed stellar and compact objects and understanding and accurately modeling plasma opacities is crucial for computational stellar astrophysics. However, there are discrepancies between observed and calculated line shapes in the high energy density (HED) regime. We explore various plasma line shape models to ascertain potential sources of these discrepancies. Current opacity models use semi-empirical molecular dynamics (MD) to simulate local particle electric fields (microfields), possibly contributing to the observed discrepancies in line shape calculations. Employing physically motivated MD models at these conditions may rectify this by improving microfield calculations. We demonstrate the microfield capabilities of LLNL's MD code ddcMD for Stark broadening calculations, in preparation for a future merge with the pre-existing line broadening program Xenomorph to enable more accurate line shape simulations.