diff --git a/devel/import_integrals/export_integrals_ao.irp.f b/devel/import_integrals/export_integrals_ao.irp.f
index ff59081..bba7ae3 100644
--- a/devel/import_integrals/export_integrals_ao.irp.f
+++ b/devel/import_integrals/export_integrals_ao.irp.f
@@ -77,6 +77,7 @@ subroutine run
     do k=1,ao_num
       do j=l,ao_num
         do i=k,ao_num
+         if (i==j .and. k<l) cycle
          if (i>=j) then
           integral = get_ao_two_e_integral(i,j,k,l,ao_integrals_map)
           if (integral /= 0.d0) then
diff --git a/devel/mpn/generate_fci.irp.f b/devel/mpn/generate_fci.irp.f
new file mode 100644
index 0000000..6a381f2
--- /dev/null
+++ b/devel/mpn/generate_fci.irp.f
@@ -0,0 +1,72 @@
+subroutine generate_fci_space
+  use bitmasks
+  implicit none
+  BEGIN_DOC
+! Generates the complete FCI space
+  END_DOC
+  integer :: i, sze, ncore
+  integer(bit_kind) :: o(N_int,2)
+  integer(bit_kind) :: u, coremask
+
+  if (mo_num > 64) then
+     stop 'No more than 64 MOs'
+  endif
+
+  ncore = 0
+  coremask = 0_bit_kind
+  do i=1,mo_num
+    if (trim(mo_class(i)) == 'Core') then
+      ncore += 1
+      coremask = ibset(coremask,i-1)
+    endif
+  enddo
+  o(1,1) = iand(full_ijkl_bitmask(1),not(coremask))
+  o(1,2) = 0_bit_kind
+
+  call configuration_to_dets_size(o,n_det_alpha_unique,elec_alpha_num-ncore,N_int)
+  TOUCH n_det_alpha_unique
+
+  integer :: k,n,m, t, t1, t2
+  k=0
+  n = elec_alpha_num
+  m = mo_num - n
+  n = n
+
+  u = shiftl(1_bit_kind,n) -1
+  do while (u < shiftl(1_bit_kind,n+m))
+    if (iand(coremask, u) == coremask) then
+      k = k+1
+      psi_det_alpha_unique(1,k) = u
+    endif
+    t = ior(u,u-1)
+    t1 = t+1
+    t2 = shiftr((iand(not(t),t1)-1), trailz(u)+1)
+    u = ior(t1,t2)
+  enddo
+
+
+  call configuration_to_dets_size(o,n_det_beta_unique,elec_beta_num-ncore,N_int)
+  TOUCH n_det_beta_unique
+
+  k=0
+  n = elec_beta_num
+  m = mo_num - n
+  u = shiftl(1_bit_kind,n) -1
+  do while (u < shiftl(1_bit_kind,n+m))
+    if (iand(coremask, u) == coremask) then
+      k = k+1
+      psi_det_beta_unique(1,k) = u
+    endif
+    t = ior(u,u-1)
+    t1 = t+1
+    t2 = shiftr((iand(not(t),t1)-1), trailz(u)+1)
+    u = ior(t1,t2)
+  enddo
+
+  call generate_all_alpha_beta_det_products
+
+  print *, N_det
+
+
+end
+
diff --git a/devel/mpn/mpn.irp.f b/devel/mpn/mpn.irp.f
index a351660..fa8c7c0 100644
--- a/devel/mpn/mpn.irp.f
+++ b/devel/mpn/mpn.irp.f
@@ -21,7 +21,11 @@ program mpn
   e_pert(1) = hf_energy - e_pert(0) - nuclear_repulsion
   do k=1,mp_order
     ! H_ij C^(k-1)
-    call h_s2_u_0_nstates_zmq(c_pert(1,k),s2,c_pert(1,k-1),1,N_det)
+    if (distributed_davidson) then
+        call H_S2_u_0_nstates_zmq   (c_pert(1,k),s2,c_pert(1,k-1),1,N_det)
+    else
+        call H_S2_u_0_nstates_openmp(c_pert(1,k),s2,c_pert(1,k-1),1,N_det)
+    endif
     if (k>1) then
       e_pert(k) += c_pert(1,k)
     endif
@@ -46,57 +50,4 @@ program mpn
 
 end
 
-subroutine generate_fci_space
-  use bitmasks
-  implicit none
-  integer :: i, sze
-  integer(bit_kind) :: o(N_int,2)
-
-  if (mo_num > 64) then
-     stop 'No more than 64 MOs'
-  endif
-  o(:,1) = full_ijkl_bitmask(:)
-  o(:,2) = 0_bit_kind
-
-  call configuration_to_dets_size(o,n_det_alpha_unique,elec_alpha_num,N_int)
-  TOUCH n_det_alpha_unique
-
-  integer :: k,n,m, t, t1, t2
-  integer(bit_kind) :: u
-  k=0
-  n = elec_alpha_num
-  m = mo_num - n
-  u = shiftl(1_bit_kind,n) -1
-  do while (u < shiftl(1_bit_kind,n+m))
-    k = k+1
-    psi_det_alpha_unique(1,k) = u
-    t = ior(u,u-1)
-    t1 = t+1
-    t2 = shiftr((iand(not(t),t1)-1), trailz(u)+1)
-    u = ior(t1,t2)
-  enddo
-
-
-  call configuration_to_dets_size(o,n_det_beta_unique,elec_beta_num,N_int)
-  TOUCH n_det_beta_unique
-
-  k=0
-  n = elec_beta_num
-  m = mo_num - n
-  u = shiftl(1_bit_kind,n) -1
-  do while (u < shiftl(1_bit_kind,n+m))
-    k = k+1
-    psi_det_beta_unique(1,k) = u
-    t = ior(u,u-1)
-    t1 = t+1
-    t2 = shiftr((iand(not(t),t1)-1), trailz(u)+1)
-    u = ior(t1,t2)
-  enddo
-
-  call generate_all_alpha_beta_det_products
-
-  print *, N_det
-
-
-end
 
diff --git a/devel/svdwf/random_svd.irp.f b/devel/svdwf/random_svd.irp.f
index 2ae76dc..5819519 100644
--- a/devel/svdwf/random_svd.irp.f
+++ b/devel/svdwf/random_svd.irp.f
@@ -88,7 +88,9 @@ subroutine run
   !$OMP PARALLEL DEFAULT(SHARED) PRIVATE(i,j,k,l)
   !$OMP DO
   do l=1,r
-    Yt(:,l) = 0.d0
+    do k=1,n
+      Yt(k,l) = 0.d0
+    enddo
     do k=1,N_det
      i = psi_bilinear_matrix_rows(k)
      j = psi_bilinear_matrix_columns(k)
diff --git a/stable/utilities/hcore_guess.irp.f b/stable/utilities/hcore_guess.irp.f
new file mode 100644
index 0000000..fdbab72
--- /dev/null
+++ b/stable/utilities/hcore_guess.irp.f
@@ -0,0 +1,4 @@
+program hcore_guess_prog
+  implicit none
+  call hcore_guess
+end