Merge pull request wannier-developers#283 from giovannipizzi/fix_278_…

…restart

Gathering matrices before dumping chk file

src/parameters.F90

@@ -3760,6 +3760,9 @@ subroutine param_write_chkpt(chkpt)
     !! Write checkpoint file
     !! IMPORTANT! If you change the chkpt format, adapt
     !! accordingly also the w90chk2chk.x utility!
+    !! Also, note that this routine writes the u_matrix and the m_matrix - in parallel
+    !! mode these are however stored in distributed form in, e.g., u_matrix_loc only, so
+    !! if you are changing the u_matrix, remember to gather it from u_matrix_loc first!
     !=================================================!
 
     use w90_io, only: io_file_unit, io_date, seedname

src/wannierise.F90

@@ -602,7 +602,17 @@ subroutine wann_main
         !omega_tilde = wann_spread%om_d + wann_spread%om_nu
       end if
 
-      if (ldump .and. on_root) call param_write_chkpt('postdis')
+      if (ldump) then
+        ! Before calling param_write_chkpt, I need to gather on the root node
+        ! the u_matrix from the u_matrix_loc. No need to broadcast it since
+        ! it's printed by the root node only
+        call comms_gatherv(u_matrix_loc, num_wann*num_wann*counts(my_node_id), &
+                           u_matrix, num_wann*num_wann*counts, num_wann*num_wann*displs)
+        ! I also transfer the M matrix
+        call comms_gatherv(m_matrix_loc, num_wann*num_wann*nntot*counts(my_node_id), &
+                           m_matrix, num_wann*num_wann*nntot*counts, num_wann*num_wann*nntot*displs)
+        if (on_root) call param_write_chkpt('postdis')
+      endif
 
       if (conv_window .gt. 1) call internal_test_convergence()