Hi, I am not sure whether this is a bug or something not yet implemented or else. I performed QM/MM simulations of a proton translocating along a water chain. This involves the breaking of a bond and the making of a new bond. The visualization of the trajectory does not show this process; instead, the original definition of bond is retained, without being updated at each timeframe. Is there a way to tell ChimeraX to automatically check covalent bonds at each snapshot and update the bond accordingly? A simple distance criterion will do. This is only for rendering purpose. In case further clarifications are needed: D—H.......A (with -- indicating the covalent bond between proton and domor and .... indicating the proximal acceptor) must be transformed to D.......H—A. Instead, it is rendered as D-------H..A (with an artificially elongated DH bond and no new HA bond) thanks s _____________________________________ Sergio A. Hassan https://bioinformatics.niaid.nih.gov/cmm/ BCBB/NIAID/NIH/DHHS 301 761 7221 (office) 301 741 5579 (mobile)