I am trying to generate the electrostatic surface for a protein that contains Mn in the 2+ state in its active site. 

I've tried to go about it in two ways but keep getting stuck.

1. If I use chimera or Pymol to use the PDB2PQR-APBS plug in, it cannot find GAFF type for Mn2+ so it cannot run anyechamber to allocate the atomic charge to Mn2+. 

Am i missing an update? Is there any way to get around this? Can I run antechamber myself to recognise my ion of interest, and then determine the charge, input it into the .pqr file and run APBS?

2. I have used the online server hosted at poissonboltzmann.org to run pdb2pqr and apps but run into the problem of not knowing what the atomic charge is for Mn2+. 

Any help would be appreciated.

Thanks!!!

Medhanjali