Dear Sir or Madam, Our protein has a bound FMN and the various tools accessible via Chimera are not able to apply charges to the atoms in FMN. However I have NBO charges for all the atoms from DFT calculations. Is there a way I can provide these to the FMN in my pdb file or in my Chimera session in order to then display a Coulomb electrostatic potential for the protein + FMN? My charges are not simply +1 or -1, but fractional charges for each atom. Can Chimera accommodate this ? If not, no problem, I will still benefit greatly even if all I can do is add -1 to the one atom at which most of the excess electron density is concentrated. Many Thanks, Anne-Frances Anne-Frances Miller Professor of Chemistry Director, Magnetic Resonance Centre University of Kentucky Dept. Chemistry, 505 Rose Street Lexington KY 40506-0055 “You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete.” Buckminster Fuller