Large Force Constants
Hello, I'm afraid I'm having some trouble with extrapolating force constants on zeolite systems from MD (FHI-aims) data. For some reason when working out the FCs on zeolite BEA I'm getting very large and unphysical looking results; however, the script/ method seems to be working fine on my other systems such as quartz and sodalite.
When inspecting the MD trajectory and data for BEA the forces all look reasonable though which leads me to be that the issue lies with the fitting/ extrapolation. Currently, my main suspicion is that it could be to do with the large unit cell of zeolite BEA (192 atoms).
Has anyone come across this issue before or have any idea what may be going wrong?
Many thanks
P.S I've attached the unphysical FCs for BEA and more reasonable looking ones for zeolite SOD (sodalite)