Hello RG Forum, towards the above topic, I am running the Orca Command: (base) Joels-MacBook-Air:14C-DON-C8i joelsubach$ orca 14C-DON-C8i.inp > 14C-DON-C8i.output.out (in this case DON means donor) to generate the above output.out file which will be subsequently used towards a VMD ffTK Charge Optimization. The above C8i .inp File exhibits a -2 Charge via its two negatively-charged carboxylate ion COO- groups generated via an Avogadro pH of 7.4 (prior the ligand exhibited instead two carboxyl group COOH groups (see screenshot attached via Dropbox Link below, figure labeled Charge-2.) I had successfully executed the above command for several other .inp files within this structure with this -2 charge within the respective .inp files, however, this C8i.inp file seems to be generating a fly-away at this proper -2 charge but when I change the C8i.inp file to a 0-charge (C8.inp) the orca command successfully generates the proper water optimization distance (see screenshots C8i_FlyAway and C8 respectively also within below Dropbox Link). Accordingly my inquiry, may I in this instance use the 0-charged .inp file exhibiting the proper water displacement out.out file or must I resolve this issue within the structure i.e. the ffTK Manual states: `Cases in which water molecules appear to settle at large distances or even “fly away”, indicate the absence of the expected minimum for the given interaction site. This can be due to improperly defined interaction type (donor vs. acceptor), secondary interactions (usually steric clashes) that destabilize the water interaction, or simply an unfavorable environment due to the local electronic structure. Observations from visual inspection can be used to troubleshoot the input settings or exclude particular target data from the optimization´.

Maybe an Orca charge adjustment of 0 is needed to modify steric clashes and or an unfavorable environment, any insight would be appreciated, thanks:) Joel 🚀