hf_calc_gradient Subroutine

   subroutine hf_calc_gradient(this, fragment, result)
      !! Calculate energy gradient 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 gradient calculation
      ! 1. Calculate energy (call calc_energy)
      ! 2. Calculate gradient using integral derivatives

      print *, "HF: Calculating gradient for fragment with", fragment%n_atoms, "atoms"

      ! First get energy
      call this%calc_energy(fragment, result)

      ! Allocate and fill dummy gradient
      allocate (result%gradient(3, fragment%n_atoms))
      result%gradient = 0.0_dp  ! Placeholder
      result%has_gradient = .true.

      print *, "HF: Dummy gradient allocated"

   end subroutine hf_calc_gradient