diff --git a/src/Dets/connections.irp.f b/src/Dets/connections.irp.f
deleted file mode 100644
index 90fbcaa8..00000000
--- a/src/Dets/connections.irp.f
+++ /dev/null
@@ -1,41 +0,0 @@
-use bitmasks
-BEGIN_PROVIDER [ integer, N_con_int ]
-  implicit none
-  BEGIN_DOC
-  ! Number of integers to represent the connections between determinants
-  END_DOC
-  N_con_int = 1 + ishft(N_det-1,-13)
-END_PROVIDER
-
-BEGIN_PROVIDER [ integer*8, det_connections, (N_con_int,N_det) ]
-  implicit none
-  BEGIN_DOC
-  !
-  END_DOC
-  integer                        :: i,j
-  integer                        :: degree
-  integer                        :: j_int, j_k, j_l
-  !$OMP PARALLEL DEFAULT (NONE) &
-  !$OMP SHARED(N_det, N_con_int, psi_det,N_int, det_connections) &
-  !$OMP PRIVATE(i,j_int,j_k,j_l,j,degree)
-  !$OMP DO SCHEDULE(guided)
-  do i=1,N_det
-    do j_int=1,N_con_int
-      det_connections(j_int,i) = 0_8
-      j_k = ishft(j_int-1,13)
-      do j_l = j_k,min(j_k+8191,N_det), 128
-        do j = j_l+1,min(j_l+128,i)
-          call get_excitation_degree(psi_det(1,1,i),psi_det(1,1,j),degree,N_int)
-          if (degree < 3) then
-            det_connections(j_int,i) = ibset( det_connections(j_int,i), iand(63,ishft(j_l,-7)) )
-            exit
-          endif
-        enddo
-      enddo
-    enddo
-  enddo
-  !$OMP ENDDO
-  !$OMP ENDPARALLEL
-
-END_PROVIDER
-
diff --git a/src/Dets/filter_connected.irp.f b/src/Dets/filter_connected.irp.f
index 058c8689..ef8358cd 100644
--- a/src/Dets/filter_connected.irp.f
+++ b/src/Dets/filter_connected.irp.f
@@ -32,7 +32,9 @@ subroutine filter_connected(key1,key2,Nint,sze,idx)
     do i=1,sze
       degree_x2 = popcnt(    xor( key1(1,1,i), key2(1,1))) &
                 + popcnt(    xor( key1(1,2,i), key2(1,2)))
-      if (degree_x2 < 5) then
+      if (degree_x2 > 4) then
+        cycle
+      else
         idx(l) = i
         l = l+1
       endif
@@ -46,7 +48,9 @@ subroutine filter_connected(key1,key2,Nint,sze,idx)
           popcnt(xor( key1(2,1,i), key2(2,1))) +                     &
           popcnt(xor( key1(1,2,i), key2(1,2))) +                     &
           popcnt(xor( key1(2,2,i), key2(2,2)))
-      if (degree_x2 < 5) then
+      if (degree_x2 > 4) then
+        cycle
+      else
         idx(l) = i
         l = l+1
       endif
@@ -62,7 +66,9 @@ subroutine filter_connected(key1,key2,Nint,sze,idx)
           popcnt(xor( key1(2,2,i), key2(2,2))) +                     &
           popcnt(xor( key1(3,1,i), key2(3,1))) +                     &
           popcnt(xor( key1(3,2,i), key2(3,2)))
-      if (degree_x2 < 5) then
+      if (degree_x2 > 4) then
+        cycle
+      else
         idx(l) = i
         l = l+1
       endif
@@ -128,11 +134,13 @@ subroutine filter_connected_davidson(key1,key2,Nint,sze,idx)
     do j_int=1,N_con_int
       itmp = det_connections(j_int,i)
       do while (itmp /= 0_8)
-        j_start = ishft(j_int-1,13) + ishft(trailz(itmp),7)
-        do j = j_start+1, min(j_start+128,i-1)
+        j_start = ishft(j_int-1,11) + ishft(trailz(itmp),5)
+        do j = j_start+1, min(j_start+32,i-1)
           degree_x2 = popcnt(xor( key1(1,1,j), key2(1,1))) +             &
               popcnt(xor( key1(1,2,j), key2(1,2)))
-          if (degree_x2 < 5) then
+          if (degree_x2 > 4) then
+            cycle
+          else
             idx(l) = j
             l = l+1
           endif
@@ -148,13 +156,15 @@ subroutine filter_connected_davidson(key1,key2,Nint,sze,idx)
     do j_int=1,N_con_int
       itmp = det_connections(j_int,i)
       do while (itmp /= 0_8)
-        j_start = ishft(j_int-1,13) + ishft(trailz(itmp),7)
-        do j = j_start+1, min(j_start+128,i-1)
+        j_start = ishft(j_int-1,11) + ishft(trailz(itmp),5)
+        do j = j_start+1, min(j_start+32,i-1)
           degree_x2 = popcnt(xor( key1(1,1,j), key2(1,1))) +         &
               popcnt(xor( key1(2,1,j), key2(2,1))) +                 &
               popcnt(xor( key1(1,2,j), key2(1,2))) +                 &
               popcnt(xor( key1(2,2,j), key2(2,2)))
-          if (degree_x2 < 5) then
+          if (degree_x2 > 4) then
+            cycle
+          else
             idx(l) = j
             l = l+1
           endif
@@ -170,15 +180,17 @@ subroutine filter_connected_davidson(key1,key2,Nint,sze,idx)
     do j_int=1,N_con_int
       itmp = det_connections(j_int,i)
       do while (itmp /= 0_8)
-        j_start = ishft(j_int-1,13) + ishft(trailz(itmp),7)
-        do j = j_start+1, min(j_start+128,i-1)
+        j_start = ishft(j_int-1,11) + ishft(trailz(itmp),5)
+        do j = j_start+1, min(j_start+32,i-1)
           degree_x2 = popcnt(xor( key1(1,1,j), key2(1,1))) +         &
               popcnt(xor( key1(1,2,j), key2(1,2))) +                 &
               popcnt(xor( key1(2,1,j), key2(2,1))) +                 &
               popcnt(xor( key1(2,2,j), key2(2,2))) +                 &
               popcnt(xor( key1(3,1,j), key2(3,1))) +                 &
               popcnt(xor( key1(3,2,j), key2(3,2)))
-          if (degree_x2 < 5) then
+          if (degree_x2 > 4) then
+            cycle
+          else
             idx(l) = j
             l = l+1
           endif
@@ -194,8 +206,8 @@ subroutine filter_connected_davidson(key1,key2,Nint,sze,idx)
     do j_int=1,N_con_int
       itmp = det_connections(j_int,i)
       do while (itmp /= 0_8)
-        j_start = ishft(j_int-1,13) + ishft(trailz(itmp),7)
-        do j = j_start+1, min(j_start+128,i-1)
+        j_start = ishft(j_int-1,11) + ishft(trailz(itmp),5)
+        do j = j_start+1, min(j_start+32,i-1)
           degree_x2 = 0
           !DEC$ LOOP COUNT MIN(4)
           do k=1,Nint
@@ -250,11 +262,11 @@ subroutine filter_connected_i_H_psi0(key1,key2,Nint,sze,idx)
     do i=1,sze
       degree_x2 = popcnt(xor( key1(1,1,i), key2(1,1))) +             &
           popcnt(xor( key1(1,2,i), key2(1,2)))
-      if (degree_x2 < 5) then
-        if(degree_x2 .ne. 0)then
-          idx(l) = i
-          l = l+1
-        endif
+      if (degree_x2 > 4) then
+        cycle
+      else if(degree_x2 .ne. 0)then
+        idx(l) = i
+        l = l+1
       endif
     enddo
     
@@ -266,11 +278,11 @@ subroutine filter_connected_i_H_psi0(key1,key2,Nint,sze,idx)
           popcnt(xor( key1(2,1,i), key2(2,1))) +                     &
           popcnt(xor( key1(1,2,i), key2(1,2))) +                     &
           popcnt(xor( key1(2,2,i), key2(2,2)))
-      if (degree_x2 < 5) then
-        if(degree_x2 .ne. 0)then
-          idx(l) = i
-          l = l+1
-        endif
+      if (degree_x2 > 4) then
+        cycle
+      else if(degree_x2 .ne. 0)then
+        idx(l) = i
+        l = l+1
       endif
     enddo
     
@@ -284,11 +296,11 @@ subroutine filter_connected_i_H_psi0(key1,key2,Nint,sze,idx)
           popcnt(xor( key1(2,2,i), key2(2,2))) +                     &
           popcnt(xor( key1(3,1,i), key2(3,1))) +                     &
           popcnt(xor( key1(3,2,i), key2(3,2)))
-      if (degree_x2 < 5) then
-        if(degree_x2 .ne. 0)then
-          idx(l) = i
-          l = l+1
-        endif
+      if (degree_x2 > 4) then
+        cycle
+      else if(degree_x2 .ne. 0)then
+        idx(l) = i
+        l = l+1
       endif
     enddo
     
@@ -305,11 +317,11 @@ subroutine filter_connected_i_H_psi0(key1,key2,Nint,sze,idx)
           exit
         endif
       enddo
-      if (degree_x2 <= 5) then
-        if(degree_x2 .ne. 0)then
+      if (degree_x2 > 4) then
+        cycle
+      else if(degree_x2 .ne. 0)then
           idx(l) = i
           l = l+1
-        endif
       endif
     enddo
     
diff --git a/src/Dets/slater_rules.irp.f b/src/Dets/slater_rules.irp.f
index 0b0ceb08..b84c47f2 100644
--- a/src/Dets/slater_rules.irp.f
+++ b/src/Dets/slater_rules.irp.f
@@ -887,3 +887,47 @@ end
 
 
 
+BEGIN_PROVIDER [ integer, N_con_int ]
+  implicit none
+  BEGIN_DOC
+  ! Number of integers to represent the connections between determinants
+  END_DOC
+  N_con_int = 1 + ishft(N_det-1,-11)
+END_PROVIDER
+
+BEGIN_PROVIDER [ integer*8, det_connections, (N_con_int,N_det) ]
+  implicit none
+  BEGIN_DOC
+  !
+  END_DOC
+  integer                        :: i,j
+  integer                        :: degree
+  integer                        :: j_int, j_k, j_l
+  integer, allocatable           :: idx(:)
+  !$OMP PARALLEL DEFAULT (NONE) &
+  !$OMP SHARED(N_det, N_con_int, psi_det,N_int, det_connections) &
+  !$OMP PRIVATE(i,j_int,j_k,j_l,j,degree,idx)
+  allocate (idx(0:N_det))
+  !$OMP DO SCHEDULE(guided)
+  do i=1,N_det
+    do j_int=1,N_con_int
+      det_connections(j_int,i) = 0_8
+      j_k = ishft(j_int-1,11)
+      do j_l = j_k,min(j_k+2047,N_det), 32 
+        do j = j_l+1,min(j_l+32,i)
+          !DIR$ FORCEINLINE
+          call get_excitation_degree(psi_det(1,1,i),psi_det(1,1,j),degree,N_int)
+          if (degree < 3) then
+            det_connections(j_int,i) = ibset( det_connections(j_int,i), iand(63,ishft(j_l,-5)) )
+            exit
+          endif
+        enddo
+      enddo
+    enddo
+  enddo
+  !$OMP ENDDO
+  deallocate(idx)
+  !$OMP ENDPARALLEL
+
+END_PROVIDER
+