Returns a Molecule centered at the center of mass.

        Returns:
            Molecule centered with center of mass at origin.

def get_centered_molecule(self):
        """
        Returns a Molecule centered at the center of mass.

        Returns:
            Molecule centered with center of mass at origin.
        """
        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)