<div><p>We report data on the structure of liquid Al and an Al<sub>67</sub>Mg<sub>33</sub> alloy obtained from state-of-the-art X-ray diffraction experiments and <i>ab initio</i> molecular dynamics (AIMD) simulations. To facilitate a direct comparison between these data, we develop a method to elongate the AIMD pair correlation function in order to obtain reliable AIMD structure factors. The comparison reveals an appreciable level of discrepancy between experimental and AIMD liquid structures, with the latter being consistently more ordered than the former at the same temperature. The discrepancy noted in this study is estimated to have significant implications for simulation-based calculations of liquid transport properties and solid–liquid interface kinetic properties.</p></div
