code: def forces(self, sets_of_forces):
          
  
          if 'first_atoms' in self._displacement_dataset:
              for disp, forces in zip(self._displacement_dataset['first_atoms'],
                                      sets_of_forces):
                  disp['forces'] = forces
          elif 'forces' in self._displacement_dataset:
              forces = np.array(sets_of_forces, dtype='double', order='C')
              self._displacement_dataset['forces'] = forces
docs: Set forces in displacement dataset.
  
          Parameters
          ----------
          sets_of_forces : array_like
              A set of atomic forces in displaced supercells. The order of
              displaced supercells has to match with that in displacement
              dataset.
              shape=(displaced supercells, atoms in supercell, 3), dtype='double'
  
              [[[f_1x, f_1y, f_1z], [f_2x, f_2y, f_2z], ...], # first supercell
               [[f_1x, f_1y, f_1z], [f_2x, f_2y, f_2z], ...], # second supercell
               ...
              ]