Periodic Efield: Test for options (Optimization, smearing) (#126)

* Periodic Efield: Test for options (Optimization, smearing)

* Pretty

src/qs_environment.F

@@ -471,7 +471,7 @@ SUBROUTINE qs_init_subsys(qs_env, para_env, subsys, cell, cell_ref, use_ref_cell
       INTEGER, DIMENSION(2)                              :: n_mo, nelectron_spin
       LOGICAL                                            :: all_potential_present, be_silent, &
                                                             do_kpoints, e1terms, has_unit_metric, &
-                                                            lribas, was_present
+                                                            lribas, orb_gradient, was_present
       REAL(dp)                                           :: ewald_rcut, maxocc, verlet_skin
       TYPE(atomic_kind_type), DIMENSION(:), POINTER      :: atomic_kind_set
       TYPE(cp_logger_type), POINTER                      :: logger
@@ -840,6 +840,19 @@ SUBROUTINE qs_init_subsys(qs_env, para_env, subsys, cell, cell_ref, use_ref_cell
       ! XXXXXXX this is backwards XXXXXXXX
       dft_control%smear = scf_control%smear%do_smear
 
+      ! Periodic efield needs equal occupation and orbital gradients
+      IF (dft_control%apply_period_efield) THEN
+         CALL get_qs_env(qs_env=qs_env, requires_mo_derivs=orb_gradient)
+         IF (.NOT. orb_gradient) THEN
+            CALL cp_abort(__LOCATION__, "Periodic Efield needs orbital gradient and direct optimization."// &
+                          " Use the OT optimization method.")
+         END IF
+         IF (dft_control%smear) THEN
+            CALL cp_abort(__LOCATION__, "Periodic Efield needs equal occupation numbers."// &
+                          " Smearing option is not possible.")
+         END IF
+      END IF
+
       !   Initialize the GAPW local densities and potentials
       IF (dft_control%qs_control%method_id == do_method_gapw .OR. &
           dft_control%qs_control%method_id == do_method_gapw_xc) THEN