The results of the structure factor from X-ray diffraction measurements are presented in Fig. with the same AIMD and NNMD simulation results weighted using X-ray atomic form factors. These partial S x αβ reveal the atomic correlations producing the scattering peaks such as the first peak at 1.7 Å -1 being comprised of Be-F and F-F that Vaslow and Narten 42 found to increase with BeF 2 concentration. The first peak measured with X-rays around 1.7 Å -1 is significantly weaker than the neutron scattering measurements because the atomic form factor for fluorine is 5 times larger than the other two atoms in FLiBe. This causes a much lower peak than measured with neutrons and is evident with the NNMD X-ray weighted results in Fig. . From the same reasoning, the second peak at 2.7 Å -1 is dominant in the X-ray measurements. The peak position and intensity in the simulated structure factors match closely with the experimental results (Fig. ). The small first peak matches better in position and intensity between NNMD simulations and X-ray scattering measurements than the second peak, which is predicted from NNMD simulations to be at slightly lower Q value and weaker intensity than was measured; the peaks at larger Q also follow this trend. The neutron results show this same shift relatively to predicted structure factor, but the difference is less pronounced. To compare all our data, we display neutron and X-ray, NNMD and AIMD partial and total g(r) and S(Q) all vertically aligned in Fig. † .