Using the hybridization information provided by the newly assigned IDATM atom types, several potential bond order states can be generated as to fit with the expected number of bonds (valence) for each ligand atom. These potential bond order assignments are evaluated in a trial and error fashion to determine whether they form a valid molecule using valence state rules derived for all atom types. The bond order set that satisfies all the requirements (see Figure ) for is used to assign GAFF bond orders to the ligand.