diff --git a/plugins/Full_CI_ZMQ/selection_davidson_slave.irp.f b/plugins/Full_CI_ZMQ/selection_davidson_slave.irp.f
index 46250be6..c1b6bcd9 100644
--- a/plugins/Full_CI_ZMQ/selection_davidson_slave.irp.f
+++ b/plugins/Full_CI_ZMQ/selection_davidson_slave.irp.f
@@ -63,7 +63,9 @@ subroutine run_wf
       ! --------
 
       print *,  'Davidson'
-      call davidson_slave_tcp(i)
+      call omp_set_nested(.True.)
+      call davidson_slave_tcp(0)
+      call omp_set_nested(.False.)
       print *,  'Davidson done'
 
     else if (trim(zmq_state) == 'pt2') then
diff --git a/src/Davidson/davidson_parallel.irp.f b/src/Davidson/davidson_parallel.irp.f
index bec6b593..09004f47 100644
--- a/src/Davidson/davidson_parallel.irp.f
+++ b/src/Davidson/davidson_parallel.irp.f
@@ -129,6 +129,8 @@ subroutine davidson_slave_work(zmq_to_qp_run_socket, zmq_socket_push, N_st, sze,
     stop 'error'
   endif
 
+  PROVIDE psi_bilinear_matrix_columns psi_bilinear_matrix_transp_rows_loc
+
   ! Run tasks
   ! ---------
 
diff --git a/src/Davidson/davidson_slave.irp.f b/src/Davidson/davidson_slave.irp.f
index e917c664..d8143958 100644
--- a/src/Davidson/davidson_slave.irp.f
+++ b/src/Davidson/davidson_slave.irp.f
@@ -10,6 +10,7 @@ program davidson_slave
   
   call provide_everything
   call switch_qp_run_to_master
+  call omp_set_nested(.True.)
   
   zmq_context = f77_zmq_ctx_new ()
   zmq_state = 'davidson'
diff --git a/src/Determinants/spindeterminants.irp.f b/src/Determinants/spindeterminants.irp.f
index 06846651..f7fd88f9 100644
--- a/src/Determinants/spindeterminants.irp.f
+++ b/src/Determinants/spindeterminants.irp.f
@@ -20,7 +20,7 @@ integer*8 function spin_det_search_key(det,Nint)
   do i=2,Nint
     spin_det_search_key = ieor(spin_det_search_key,det(i))
   enddo
-  spin_det_search_key = spin_det_search_key+1_bit_kind-unsigned_shift
+  spin_det_search_key = spin_det_search_key+unsigned_shift
 end
 
 
@@ -414,7 +414,8 @@ BEGIN_PROVIDER  [ double precision, psi_bilinear_matrix_values, (N_det,N_states)
   do k=1,N_det
     i = get_index_in_psi_det_alpha_unique(psi_det(1,1,k),N_int)
     j = get_index_in_psi_det_beta_unique (psi_det(1,2,k),N_int)
-
+    if (i < 1) stop 'i<1'
+    if (j < 1) stop 'j<1'
     do l=1,N_states
       psi_bilinear_matrix_values(k,l) = psi_coef(k,l)
     enddo
@@ -471,6 +472,9 @@ BEGIN_PROVIDER [ integer, psi_bilinear_matrix_columns_loc, (N_det_beta_unique+1)
       l = psi_bilinear_matrix_columns(k)
       psi_bilinear_matrix_columns_loc(l) = k
     endif
+    if (psi_bilinear_matrix_columns(k) < 1) then
+     stop '(psi_bilinear_matrix_columns(k) < 1)'
+    endif
   enddo
   psi_bilinear_matrix_columns_loc(N_det_beta_unique+1) = N_det+1
 END_PROVIDER
@@ -496,17 +500,23 @@ BEGIN_PROVIDER  [ double precision, psi_bilinear_matrix_transp_values, (N_det,N_
   integer*8, allocatable :: to_sort(:)
   allocate(to_sort(N_det))
   !$OMP PARALLEL DEFAULT(SHARED) PRIVATE(i,j,k,l)
-  !$OMP DO COLLAPSE(2)
   do l=1,N_states
+    !$OMP DO
     do k=1,N_det
       psi_bilinear_matrix_transp_values (k,l) = psi_bilinear_matrix_values (k,l)
     enddo
+    !$OMP ENDDO
   enddo
-  !$OMP ENDDO 
   !$OMP DO 
   do k=1,N_det
     psi_bilinear_matrix_transp_columns(k) = psi_bilinear_matrix_columns(k)
+    if (psi_bilinear_matrix_transp_columns(k) < 1) then
+     stop '(psi_bilinear_matrix_transp_columns(k) < 1)'
+    endif
     psi_bilinear_matrix_transp_rows   (k) = psi_bilinear_matrix_rows   (k)
+    if (psi_bilinear_matrix_transp_rows(k) < 1) then
+     stop '(psi_bilinear_matrix_transp_rows(k) < 1)'
+    endif
     i = psi_bilinear_matrix_transp_columns(k) 
     j = psi_bilinear_matrix_transp_rows   (k)
     to_sort(k) = int(N_det_beta_unique,8) * int(j-1,8) + int(i,8)