Unpredictable Ngm in phonons

Apparently in parallel phonon calculations the local value of 'ngm' may vary
between a q-vector and the following one. This may lead to OOB in the 2D case.
May be related to issue 488.

LR_Modules/Coul_cut_2D_ph.f90

@@ -32,6 +32,7 @@ MODULE Coul_cut_2D_ph
   ! 
   !
   PUBLIC :: cutoff_fact_qg, cutoff_lr_Vlocq, cutoff_localq
+  PUBLIC :: deallocate_2d_arrays
   
 CONTAINS
 !
@@ -228,4 +229,10 @@ subroutine cutoff_dynmat0 (dynwrk, rhog)
   ENDDO  
   return
 end subroutine cutoff_dynmat0
+
+subroutine deallocate_2d_arrays ()
+  IF ( allocated(cutoff_2D_qg) ) DEALLOCATE(cutoff_2D_qg)
+  IF ( allocated(lr_Vlocq)     ) DEALLOCATE(lr_Vlocq)
+end subroutine deallocate_2d_arrays
+
 END MODULE Coul_cut_2D_ph

PHonon/PH/deallocate_phq.f90

@@ -45,6 +45,7 @@ subroutine deallocate_phq
   USE qpoint_aux,   ONLY : ikmks, ikmkmqs, becpt, alphapt
   USE becmod,       ONLY : deallocate_bec_type
   USE nc_mag_aux,   ONLY : int1_nc_save, deeq_nc_save
+  USE Coul_cut_2D_ph, ONLY : deallocate_2d_arrays
 
   IMPLICIT NONE
   INTEGER :: ik, ipol
@@ -194,6 +195,6 @@ subroutine deallocate_phq
      !
   ENDIF
 
-  RETURN
+  call deallocate_2d_arrays ()
  
 end subroutine deallocate_phq

PHonon/PH/phq_init.f90

@@ -130,7 +130,7 @@ SUBROUTINE phq_init()
   ! component of the cutoff of the COulomb interaction
   IF (do_cutoff_2D) call cutoff_fact_qg() 
   !  in 2D calculations the long range part of vlocq(g) (erf/r part)
-  ! was not re-added in g-space because everything is caclulated in
+  ! was not re-added in g-space because everything is calculated in
   ! radial coordinates, which is not compatible with 2D cutoff. 
   ! It will be re-added each time vlocq(g) is used in the code. 
   ! Here, this cutoff long-range part of vlocq(g) is computed only once