diff --git a/plugins/FourIdx/four_index_sym.irp.f b/plugins/FourIdx/four_index_sym.irp.f
index 597395a6..ffab74e5 100644
--- a/plugins/FourIdx/four_index_sym.irp.f
+++ b/plugins/FourIdx/four_index_sym.irp.f
@@ -31,6 +31,7 @@ subroutine four_index_transform_sym(map_a,map_c,matrix_B,LDB,            &
   real(integral_kind)            :: tmp
   integer(key_kind), allocatable :: key(:)
   real(integral_kind), allocatable :: value(:)
+  integer*8, allocatable         :: l_pointer(:)
 
   ASSERT (k_start == i_start)
   ASSERT (l_start == j_start)
@@ -58,48 +59,71 @@ subroutine four_index_transform_sym(map_a,map_c,matrix_B,LDB,            &
   ! Create a temporary memory-mapped file
   integer                        :: fd
   type(c_ptr)                    :: c_pointer
-  integer*8, pointer             :: a_array(:,:)
+  integer*8, pointer             :: a_array(:)
   call mmap(trim(ezfio_filename)//'/work/four_idx',                  &
-      (/ (int(i_end-i_start+1,8)*int(j_end-j_start+2,8)*int(k_end-k_start+1,8)),int(l_end-l_start+1,8) /), 16, fd, .False., c_pointer)
-  call c_f_pointer(c_pointer, a_array, (/ ((i_end-i_start+1)*(j_end-j_start+1)*(k_end-k_start+1)*3_8)/2_8, l_end-l_start+1_8 /))
+      (/ 12_8 * map_a % n_elements /), 8, fd, .False., c_pointer)
+  call c_f_pointer(c_pointer, a_array, (/ 12_8 * map_a % n_elements /))
+
+  allocate(l_pointer(l_start:l_end+1))
+
+!  !$OMP PARALLEL DO DEFAULT(SHARED) PRIVATE(i) SCHEDULE(static,137)
+!  do i=1,size(a_array)
+!    a_array(i) = 0.d0
+!  enddo
+!  !$OMP END PARALLEL  DO
+
+  allocate( value((i_max*k_max)) )
+  a = 1
+  !$OMP PARALLEL DEFAULT(SHARED) PRIVATE(i,j,k,l,ik,idx) 
+  do l=l_start,l_end
+    !$OMP SINGLE
+    l_pointer(l) = a
+    !$OMP END SINGLE
+    do j=j_start,j_end
+      !$OMP DO SCHEDULE(static,1)
+      do k=k_start,k_end
+        do i=i_start,k
+          ik = (i-i_start+1) + ishft( (k-k_start)*(k-k_start+1), -1 )
+          call bielec_integrals_index(i,j,k,l,idx)
+          call map_get(map_a,idx,value(ik))
+        enddo
+      enddo
+      !$OMP END DO
+
+      !$OMP SINGLE
+      ik=0
+      do k=k_start,k_end
+        do i=i_start,k
+          ik = ik+1
+          tmp=value(ik)
+          if (tmp /= 0.d0) then
+            a_array(a) = ik
+            a = a+1
+            a_array(a) = j
+            a = a+1
+            a_array(a) = transfer(dble(tmp), 1_8)
+            a = a+1
+          endif
+        enddo
+      enddo
+      !$OMP END SINGLE
+    enddo
+  enddo
+  !$OMP END PARALLEL  
+  l_pointer(l_end+1) = a
+  deallocate(value)
 
   !$OMP PARALLEL DEFAULT(NONE) SHARED(a_array,c_pointer,fd,          &
       !$OMP  a_start,a_end,b_start,b_end,c_start,c_end,d_start,d_end,&
       !$OMP  i_start,i_end,j_start,j_end,k_start,k_end,l_start,l_end,&
       !$OMP  i_min,i_max,j_min,j_max,k_min,k_max,l_min,l_max,        &
-      !$OMP  map_a,map_c,matrix_B)                                   &
+      !$OMP  map_a,map_c,matrix_B,l_pointer)                         &
       !$OMP  PRIVATE(key,value,T,U,V,i,j,k,l,idx,ik,ll,   &
       !$OMP  a,b,c,d,tmp,T2d,V2d)
   allocate( key(i_max*j_max*k_max), value(i_max*j_max*k_max) )
   allocate( U(a_start:a_end, c_start:c_end, b_start:b_end) )
 
 
-  !$OMP DO SCHEDULE(dynamic,4)
-  do l=l_start,l_end
-    a = 1
-    ll = l-l_start+1
-    do j=j_start,j_end
-      ik=0
-      do k=k_start,k_end
-        do i=i_start,k
-          ik = ik+1
-          call bielec_integrals_index(i,j,k,l,idx)
-          call map_get(map_a,idx,tmp)
-          if (tmp /= 0.d0) then
-            a = a+1
-            a_array(a,ll) = ik
-            a = a+1
-            a_array(a,ll) = j
-            a = a+1
-            a_array(a,ll) = transfer(dble(tmp), 1_8)
-          endif
-        enddo
-      enddo
-    enddo
-    a_array(a+1,ll) = 0
-    a_array(1,ll) = a
-  enddo
-  !$OMP END DO
 
   allocate( T2d((i_end-i_start+1)*(k_end-k_start+2)/2, j_start:j_end), &
             V2d((i_end-i_start+1)*(k_end-k_start+2)/2, b_start:b_end), &
@@ -115,24 +139,17 @@ subroutine four_index_transform_sym(map_a,map_c,matrix_B,LDB,            &
         cycle
       endif
       
-      ll = l-l_start+1
-!      T2d = 0.d0
-!      do a=2,a_array(1,ll),3
-!        ik = a_array(a,ll)
-!        j = a_array(a+1,ll)
-!        T2d(ik,j) = transfer(a_array(a+2,ll), 1.d0)
-!      enddo
-
-      a=2
+      a=l_pointer(l)
       do j=j_start,j_end
         ik=0
         do k=k_start,k_end
           do i=i_start,k
             ik = ik+1
-            if ( (ik /= a_array(a,ll)).or.(j /= a_array(a+1,ll)) ) then
+            if ( (ik /= a_array(a)).or.(j /= a_array(a+1))  &
+                 .or.(a >= l_pointer(l+1)) ) then
               T2d(ik,j) = 0.d0
             else
-              T2d(ik,j) = transfer(a_array(a+2,ll), 1.d0)
+              T2d(ik,j) = transfer(a_array(a+2), 1.d0)
               a=a+3
             endif
           enddo
@@ -228,6 +245,7 @@ subroutine four_index_transform_sym(map_a,map_c,matrix_B,LDB,            &
   call map_sort(map_c)
 
   call munmap( &
-      (/ (int(i_end-i_start+1,8)*int(j_end-j_start+2,8)*int(k_end-k_start+1,8)),int(l_end-l_start+1,8) /), 16, fd, c_pointer)
+      (/ 12_8 * map_a % n_elements /), 8, fd, c_pointer)
+  deallocate(l_pointer)
 
 end