Hi Jan, We have the N-Gaussians for all ions that appear in the International Tables Volume C. You can find the source code for the compiled-in tables here: cctbx/eltbx/xray_scattering
RuntimeError: gaussian not defined for scattering_type "Y4+".
RuntimeError: gaussian not defined for scattering_type "V4+". RuntimeError: gaussian not defined for scattering_type "H1+".
These three do not appear in the Int. Tables. We'd need to find out what form factors were actually used in the refinement. I see the structures are from 1981-1993. It could be very difficult to find out for sure. We already have an option to make the form factor lookup less strict. The critical line is this in cctbx/xray/structure.py: std_lbl = eltbx.xray_scattering.get_standard_label( label=t_undef, exact=True, optional=True) I think your script should run if you set exact=False, but it will use plain Y, V, H form factors for the unknown ions. Is that good enough for your purposes? Ralf