code: def get_centered_molecule(self):
          
          center = self.center_of_mass
          new_coords = np.array(self.cart_coords) - center
          return self.__class__(self.species_and_occu, new_coords,
                                charge=self._charge,
                                spin_multiplicity=self._spin_multiplicity,
                                site_properties=self.site_properties)
docs: Returns a Molecule centered at the center of mass.
  
          Returns:
              Molecule centered with center of mass at origin.