~/Code/RMG-Py/arkane/main.py in execute(self)
    207                 job.execute(output_directory=self.output_directory, plot=self.plot)
    208             if isinstance(job, StatMechJob):
--> 209                 job.execute(output_directory=self.output_directory, plot=self.plot, pdep=is_pdep(self.job_list))
    210                 if hasattr(job, 'supporting_info'):
    211                     supporting_info.append(job.supporting_info)

~/Code/RMG-Py/arkane/statmech.py in execute(self, output_directory, plot, pdep)
    205         If `plot` is True, then plots of the hindered rotor fits will be saved.
    206         """
--> 207         self.load(pdep, plot)
    208         if output_directory is not None:
    209             try:

~/Code/RMG-Py/arkane/statmech.py in load(self, pdep, plot)
    419         else:
    420             # Sometimes the translational mode is not appended to modes for monoatomic species
--> 421             conformer.modes.append(IdealGasTranslation(mass=self.species.molecular_weight))
    422 
    423         if conformer.spin_multiplicity == 0:

AttributeError: 'rmgpy.species.TransitionState' object has no attribute 'molecular_weight'