diff --git a/src/Davidson/u0Hu0.irp.f b/src/Davidson/u0Hu0.irp.f
index cf28cf12..c7592fad 100644
--- a/src/Davidson/u0Hu0.irp.f
+++ b/src/Davidson/u0Hu0.irp.f
@@ -88,7 +88,7 @@ subroutine H_u_0_nstates(v_0,u_0,H_jj,n,keys_tmp,Nint,N_st,sze_8)
   
   !$OMP DO SCHEDULE(dynamic)
   do sh=1,shortcut(0,1)
-    do sh2=sh,shortcut(0,1)
+    do sh2=1,shortcut(0,1)
       exa = popcnt(xor(version(1,sh,1), version(1,sh2,1)))
       if(exa > 2) then
         cycle
@@ -102,16 +102,11 @@ subroutine H_u_0_nstates(v_0,u_0,H_jj,n,keys_tmp,Nint,N_st,sze_8)
       
       do i=shortcut(sh,1),shortcut(sh+1,1)-1
         org_i = sort_idx(i,1)
-        if(sh==sh2) then
-          endi = i-1
-        else
-          endi = shortcut(sh2+1,1)-1
-        end if
         do ni=1,Nint
           sorted_i(ni) = sorted(ni,i,1)
         enddo
         
- jloop: do j=shortcut(sh2,1),endi
+ jloop: do j=shortcut(sh2,1),shortcut(sh2+1,1)-1
           org_j = sort_idx(j,1)
           ext = exa + popcnt(xor(sorted_i(1), sorted(1,j,1)))
           if(ext > 4) then
@@ -126,7 +121,6 @@ subroutine H_u_0_nstates(v_0,u_0,H_jj,n,keys_tmp,Nint,N_st,sze_8)
           call i_H_j(keys_tmp(1,1,org_j),keys_tmp(1,1,org_i),Nint,hij)
           do istate=1,N_st
             vt (istate,org_i) = vt (istate,org_i) + hij*ut(istate,org_j)
-            vt (istate,org_j) = vt (istate,org_j) + hij*ut(istate,org_i)
           enddo
         enddo jloop
       enddo
@@ -138,7 +132,7 @@ subroutine H_u_0_nstates(v_0,u_0,H_jj,n,keys_tmp,Nint,N_st,sze_8)
   do sh=1,shortcut(0,2)
     do i=shortcut(sh,2),shortcut(sh+1,2)-1
       org_i = sort_idx(i,2)
-      do j=shortcut(sh,2),i-1
+      do j=shortcut(sh,2),shortcut(sh+1,2)-1
         org_j = sort_idx(j,2)
         ext = popcnt(xor(sorted(1,i,2), sorted(1,j,2)))
         do ni=2,Nint
@@ -150,7 +144,6 @@ subroutine H_u_0_nstates(v_0,u_0,H_jj,n,keys_tmp,Nint,N_st,sze_8)
         call i_H_j(keys_tmp(1,1,org_j),keys_tmp(1,1,org_i),Nint,hij)
         do istate=1,N_st
           vt (istate,org_i) = vt (istate,org_i) + hij*ut(istate,org_j)
-          vt (istate,org_j) = vt (istate,org_j) + hij*ut(istate,org_i)
         enddo
       end do
     end do
@@ -336,27 +329,29 @@ subroutine H_S2_u_0_nstates(v_0,s_0,u_0,H_jj,S2_jj,n,keys_tmp,Nint,N_st,sze_8)
   v_0 = 0.d0
   s_0 = 0.d0
 
-  do i=1,n
-    do istate=1,N_st
-      ut(istate,i) = u_0(i,istate)
-    enddo
-  enddo
-
   call sort_dets_ab_v(keys_tmp, sorted(1,1,1), sort_idx(1,1), shortcut(0,1), version(1,1,1), n, Nint)
   call sort_dets_ba_v(keys_tmp, sorted(1,1,2), sort_idx(1,2), shortcut(0,2), version(1,1,2), n, Nint)
 
   !$OMP PARALLEL DEFAULT(NONE)                                       &
       !$OMP PRIVATE(i,hij,s2,j,k,jj,vt,st,ii,sh,sh2,ni,exa,ext,org_i,org_j,endi,sorted_i,istate)&
-      !$OMP SHARED(n,keys_tmp,ut,Nint,v_0,s_0,sorted,shortcut,sort_idx,version,N_st,N_st_8) 
+      !$OMP SHARED(n,keys_tmp,ut,Nint,u_0,v_0,s_0,sorted,shortcut,sort_idx,version,N_st,N_st_8) 
   allocate(vt(N_st_8,n),st(N_st_8,n))
   Vt = 0.d0
   St = 0.d0
 
-  !$OMP DO SCHEDULE(dynamic)
+  !$OMP DO
+  do i=1,n
+    do istate=1,N_st
+      ut(istate,i) = u_0(sort_idx(i,2),istate)
+    enddo
+  enddo
+  !$OMP END DO
+
+  !$OMP DO SCHEDULE(dynamic) 
   do sh=1,shortcut(0,2)
     do i=shortcut(sh,2),shortcut(sh+1,2)-1
       org_i = sort_idx(i,2)
-      do j=shortcut(sh,2),i-1
+      do j=shortcut(sh,2),shortcut(sh+1,2)-1
         org_j = sort_idx(j,2)
         ext = popcnt(xor(sorted(1,i,2), sorted(1,j,2)))
         if (ext > 4) cycle
@@ -368,19 +363,26 @@ subroutine H_S2_u_0_nstates(v_0,s_0,u_0,H_jj,S2_jj,n,keys_tmp,Nint,N_st,sze_8)
             call i_h_j (keys_tmp(1,1,org_j),keys_tmp(1,1,org_i),nint,hij)
             call get_s2(keys_tmp(1,1,org_j),keys_tmp(1,1,org_i),nint,s2)
             do istate=1,n_st
-              vt (istate,org_i) = vt (istate,org_i) + hij*ut(istate,org_j)
-              vt (istate,org_j) = vt (istate,org_j) + hij*ut(istate,org_i)
-              st (istate,org_i) = st (istate,org_i) + s2*ut(istate,org_j)
-              st (istate,org_j) = st (istate,org_j) + s2*ut(istate,org_i)
+              vt (istate,org_i) = vt (istate,org_i) + hij*ut(istate,j)
+              st (istate,org_i) = st (istate,org_i) + s2*ut(istate,j)
             enddo
         end if
       end do
     end do
   enddo
-  !$OMP END DO NOWAIT
+  !$OMP END DO
+
+  !$OMP DO
+  do i=1,n
+    do istate=1,N_st
+      ut(istate,i) = u_0(sort_idx(i,1),istate)
+    enddo
+  enddo
+  !$OMP END DO
+
+  !$OMP DO SCHEDULE(dynamic)
   do sh=1,shortcut(0,1)
-    !$OMP DO SCHEDULE(dynamic)
-    do sh2=sh,shortcut(0,1)
+    do sh2=1,shortcut(0,1)
       exa = 0
       do ni=1,Nint
         exa = exa + popcnt(xor(version(ni,sh,1), version(ni,sh2,1)))
@@ -391,16 +393,12 @@ subroutine H_S2_u_0_nstates(v_0,s_0,u_0,H_jj,S2_jj,n,keys_tmp,Nint,N_st,sze_8)
 
       do i=shortcut(sh,1),shortcut(sh+1,1)-1
         org_i = sort_idx(i,1)
-        if(sh==sh2) then
-          endi = i-1
-        else
-          endi = shortcut(sh2+1,1)-1
-        end if
         do ni=1,Nint
           sorted_i(ni) = sorted(ni,i,1)
         enddo
 
-        do j=shortcut(sh2,1),endi
+        do j=shortcut(sh2,1),shortcut(sh2+1,1)-1
+          if (i==j) cycle
           ext = exa + popcnt(xor(sorted_i(1), sorted(1,j,1)))
           if (ext > 4) cycle
           do ni=2,Nint
@@ -412,16 +410,14 @@ subroutine H_S2_u_0_nstates(v_0,s_0,u_0,H_jj,S2_jj,n,keys_tmp,Nint,N_st,sze_8)
             call i_h_j (keys_tmp(1,1,org_j),keys_tmp(1,1,org_i),nint,hij)
             if (hij /= 0.d0) then
               do istate=1,n_st
-                vt (istate,org_i) = vt (istate,org_i) + hij*ut(istate,org_j)
-                vt (istate,org_j) = vt (istate,org_j) + hij*ut(istate,org_i)
+                vt (istate,org_i) = vt (istate,org_i) + hij*ut(istate,j)
               enddo
             endif
             if (ext /= 2) then
               call get_s2(keys_tmp(1,1,org_j),keys_tmp(1,1,org_i),nint,s2)
               if (s2 /= 0.d0) then
                 do istate=1,n_st
-                  st (istate,org_i) = st (istate,org_i) + s2*ut(istate,org_j)
-                  st (istate,org_j) = st (istate,org_j) + s2*ut(istate,org_i)
+                  st (istate,org_i) = st (istate,org_i) + s2*ut(istate,j)
                 enddo
               endif
             endif
@@ -429,8 +425,8 @@ subroutine H_S2_u_0_nstates(v_0,s_0,u_0,H_jj,S2_jj,n,keys_tmp,Nint,N_st,sze_8)
         enddo
       enddo
     enddo
-    !$OMP END DO NOWAIT
   enddo
+  !$OMP END DO 
 
   !$OMP CRITICAL (u0Hu0)
   do istate=1,N_st