code: def displacements(self, displacements):
          
  
          disp = np.array(displacements, dtype='double', order='C')
          if (disp.ndim != 3 or
              disp.shape[1:] != (self._supercell.get_number_of_atoms(), 3)):
              raise RuntimeError("Array shape of displacements is incorrect.")
  
          if 'first_atoms' in self._displacement_dataset:
              raise RuntimeError("This displacement format is not supported.")
  
          self._displacement_dataset['displacements'] = disp
docs: Set displacemens
  
          Parameters
          ----------
          displacemens : array_like
              Atomic displacements of all atoms of all supercells.
              Only all displacements in each supercell case is supported.
              shape=(supercells, natom, 3), dtype='double', order='C'