code: def hessian(self):
          
          result = np.zeros((self.numc, 3, self.numc, 3), float)
          for index1 in range(self.numc):
              for index2 in range(self.numc):
                  result[index1, :, index2, :] = self.hessian_component(index1, index2)
          return result
docs: Compute the hessian of the energy