diff --git a/config/gfortran_avx.cfg b/config/gfortran_avx.cfg
index 80bbbec9..f065d133 100644
--- a/config/gfortran_avx.cfg
+++ b/config/gfortran_avx.cfg
@@ -10,7 +10,7 @@
 #
 #
 [COMMON]
-FC           : gfortran -ffree-line-length-none -I . -mavx -g
+FC           : gfortran -ffree-line-length-none -I . -mavx -g 
 LAPACK_LIB   : -llapack -lblas
 IRPF90       : irpf90
 IRPF90_FLAGS : --ninja --align=32
@@ -35,7 +35,7 @@ OPENMP  : 1          ; Append OpenMP flags
 #                           -ffast-math and the Fortran-specific
 #                           -fno-protect-parens and -fstack-arrays.
 [OPT]
-FCFLAGS : -Ofast 
+FCFLAGS : -Ofast -march=native
 
 # Profiling flags
 #################
diff --git a/plugins/Full_CI_ZMQ/energy.irp.f b/plugins/Full_CI_ZMQ/energy.irp.f
index 7b7cc75b..5f9baf46 100644
--- a/plugins/Full_CI_ZMQ/energy.irp.f
+++ b/plugins/Full_CI_ZMQ/energy.irp.f
@@ -12,7 +12,7 @@ BEGIN_PROVIDER [ double precision, pt2_E0_denominator, (N_states) ]
  ! E0 in the denominator of the PT2
  END_DOC
  if (initialize_pt2_E0_denominator) then
-  pt2_E0_denominator(1:N_states) = CI_electronic_energy(1:N_states)
+  pt2_E0_denominator(1:N_states) = psi_energy(1:N_states)
 ! pt2_E0_denominator(1:N_states) = HF_energy - nuclear_repulsion
 ! pt2_E0_denominator(1:N_states) = barycentric_electronic_energy(1:N_states)
   call write_double(6,pt2_E0_denominator(1)+nuclear_repulsion, 'PT2 Energy denominator')
diff --git a/plugins/Full_CI_ZMQ/pt2_stoch.irp.f b/plugins/Full_CI_ZMQ/pt2_stoch.irp.f
index 8ffd8e60..49902696 100644
--- a/plugins/Full_CI_ZMQ/pt2_stoch.irp.f
+++ b/plugins/Full_CI_ZMQ/pt2_stoch.irp.f
@@ -1,8 +1,7 @@
 program pt2_stoch
   implicit none
-  initialize_pt2_E0_denominator = .False.
   read_wf = .True.
-  SOFT_TOUCH initialize_pt2_E0_denominator read_wf
+  SOFT_TOUCH read_wf
   PROVIDE mo_bielec_integrals_in_map
   call run
 end
@@ -19,17 +18,12 @@ subroutine run
 
   double precision               :: E_CI_before(N_states), relative_error
 
-  if (.true.) then
-    call ezfio_get_full_ci_zmq_energy(E_CI_before(1))
-    pt2_e0_denominator(:) = E_CI_before(1) - nuclear_repulsion
-    SOFT_TOUCH pt2_e0_denominator read_wf
-  endif
   allocate (pt2(N_states))
   pt2 = 0.d0
   
   threshold_selectors = 1.d0
   threshold_generators = 1d0 
-  relative_error = 1.d-6
+  relative_error = 1.d-4
   call ZMQ_pt2(pt2, relative_error)
   print *,  'Final step'
   print *,  'N_det    = ', N_det
diff --git a/src/Determinants/slater_rules.irp.f b/src/Determinants/slater_rules.irp.f
index 62493ab9..a3a647ac 100644
--- a/src/Determinants/slater_rules.irp.f
+++ b/src/Determinants/slater_rules.irp.f
@@ -18,24 +18,33 @@ subroutine get_excitation_degree(key1,key2,degree,Nint)
   select case (Nint)
 
     case (1)
-      xorvec(1:2) = xor( key1(1:2), key2(1:2))
+      xorvec(1) = xor( key1(1), key2(1))
+      xorvec(2) = xor( key1(2), key2(2))
       degree = sum(popcnt(xorvec(1:2)))
 
     case (2)
-      xorvec(1:4) = xor( key1(1:4), key2(1:4))
+      xorvec(1) = xor( key1(1), key2(1))
+      xorvec(2) = xor( key1(2), key2(2))
+      xorvec(3) = xor( key1(3), key2(3))
+      xorvec(4) = xor( key1(4), key2(4))
       degree = sum(popcnt(xorvec(1:4)))
 
     case (3)
-      xorvec(1:6) = xor( key1(1:6), key2(1:6))
+      do l=1,6
+        xorvec(l) = xor( key1(l), key2(l))
+      enddo
       degree = sum(popcnt(xorvec(1:6)))
 
     case (4)
-      xorvec(1:8) = xor( key1(1:8), key2(1:8))
+      do l=1,8
+        xorvec(l) = xor( key1(l), key2(l))
+      enddo
       degree = sum(popcnt(xorvec(1:8)))
 
     case default
-      l = ishft(Nint,1)
-      xorvec(1:l) = xor( key1(1:l), key2(1:l))
+      do l=1,ishft(Nint,1)
+        xorvec(l) = xor( key1(l), key2(l))
+      enddo
       degree = sum(popcnt(xorvec(1:l)))
   
   end select
@@ -2254,19 +2263,27 @@ subroutine get_excitation_degree_spin(key1,key2,degree,Nint)
       degree = popcnt(xorvec(1))
 
     case (2)
-      xorvec(1:2) = xor( key1(1:2), key2(1:2))
-      degree = sum(popcnt(xorvec(1:2)))
+      xorvec(1) = xor( key1(1), key2(1))
+      xorvec(2) = xor( key1(2), key2(2))
+      degree = popcnt(xorvec(1))+popcnt(xorvec(2))
 
     case (3)
-      xorvec(1:3) = xor( key1(1:3), key2(1:3))
+      xorvec(1) = xor( key1(1), key2(1))
+      xorvec(2) = xor( key1(2), key2(2))
+      xorvec(3) = xor( key1(3), key2(3))
       degree = sum(popcnt(xorvec(1:3)))
 
     case (4)
-      xorvec(1:4) = xor( key1(1:4), key2(1:4))
+      xorvec(1) = xor( key1(1), key2(1))
+      xorvec(2) = xor( key1(2), key2(2))
+      xorvec(3) = xor( key1(3), key2(3))
+      xorvec(4) = xor( key1(4), key2(4))
       degree = sum(popcnt(xorvec(1:4)))
 
     case default
-      xorvec(1:Nint) = xor( key1(1:Nint), key2(1:Nint))
+      do l=1,N_int
+        xorvec(l) = xor( key1(l), key2(l))
+      enddo
       degree = sum(popcnt(xorvec(1:Nint)))
   
   end select