null_hessian Subroutine

   subroutine null_hessian(this, fragment, result)
      !! Placeholder for Hessian calculation
      class(hf_method_t), intent(in) :: this
      type(physical_fragment_t), intent(in) :: fragment
      type(calculation_result_t), intent(out) :: result

      print *, "HF: Hessian calculation not implemented yet."
      result%has_hessian = .false.

   end subroutine null_hessian