[ccp4bb] Restraints in Refmac5

Hi everyone, I am refining a protein structure containing a Beryllium Fluoride (BeF3) ligand.  I am using Refmac5 in ccp4i.   The distances between the Be and the F atoms  are slightly longer than what I would expect (1.7A instead of ~1.5A). Does anyone know how I can fix the distances and rest

[ccp4bb]

Hi everyone, I am refining a protein structure containing a Beryllium Fluoride (BeF3) ligand.  I am using Refmac5 in ccp4i.   The distances between the Be and the F atoms  are slightly longer than what I would expect (1.7A instead of ~1.5A). Does anyone know how I can fix the distances and rest