hf_calc_energy Subroutine

   subroutine hf_calc_energy(this, fragment, result)
      !! Calculate electronic energy using Hartree-Fock method
      class(hf_method_t), intent(in) :: this
      type(physical_fragment_t), intent(in) :: fragment
      type(calculation_result_t), intent(out) :: result

      ! DUMMY IMPLEMENTATION
      ! TODO: Implement actual HF calculation
      ! 1. Convert fragment%basis to libcint format
      ! 2. Build one-electron integrals (S, T, V)
      ! 3. Run SCF iterations
      ! 4. Calculate final energy

      print *, "HF: Calculating energy for fragment with", fragment%n_atoms, "atoms"
      print *, "HF: nelec =", fragment%nelec
      print *, "HF: charge =", fragment%charge
      print *, "HF: multiplicity =", fragment%multiplicity

      ! Dummy result
      result%energy%scf = -1.0_dp  ! Placeholder
      result%has_energy = .true.

      print *, "HF: Dummy energy =", result%energy%total()

   end subroutine hf_calc_energy