diff --git a/configure b/configure
index a8f6cc9e..de5b3d56 100755
--- a/configure
+++ b/configure
@@ -142,7 +142,7 @@ ezfio = Info(
     default_path=join(QP_ROOT_INSTALL, "EZFIO"))
 
 zeromq = Info(
-    url='http://download.zeromq.org/zeromq-4.0.7.tar.gz',
+    url='https://github.com/zeromq/zeromq4-1/releases/download/v4.1.4/zeromq-4.1.4.tar.gz',
     description=' ZeroMQ',
     default_path=join(QP_ROOT_LIB, "libzmq.a"))
 
diff --git a/src/Determinants/s2.irp.f b/src/Determinants/s2.irp.f
index 9810b219..400b373e 100644
--- a/src/Determinants/s2.irp.f
+++ b/src/Determinants/s2.irp.f
@@ -234,7 +234,7 @@ subroutine get_uJ_s2_uI(psi_keys_tmp,psi_coefs_tmp,n,nmax_coefs,nmax_keys,s2,nst
   do jj = 1, nstates
  accu = 0.d0
  !$OMP PARALLEL DEFAULT(NONE)                                         &
- !$OMP PRIVATE (i,j,kk,idx,tmp,s2_tmp) & 
+ !$OMP PRIVATE (i,j,kk,idx,tmp,s2_tmp,accu) & 
  !$OMP SHARED (ll,jj,psi_keys_tmp,psi_coefs_tmp,N_int,n,nstates)      &
  !$OMP REDUCTION(+:accu)
  allocate(idx(0:n))
@@ -301,13 +301,19 @@ subroutine diagonalize_s2_betweenstates(keys_tmp,psi_coefs_inout,n,nmax_keys,nma
  print*,''
  print*,'nstates = ',nstates
  allocate(s2(nstates,nstates),overlap(nstates,nstates))
+ !$OMP PARALLEL DO COLLAPSE(2) DEFAULT(NONE) &
+ !$OMP  PRIVATE(i,j) SHARED(overlap,psi_coefs_inout,nstates,n)
   do i = 1, nstates
-    overlap(i,i) = u_dot_u(psi_coefs_inout(1,i),n)
     do j = i+1, nstates
-      overlap(i,j) = u_dot_v(psi_coefs_inout(1,j),psi_coefs_inout(1,i),n)
-      overlap(j,i) = overlap(i,j)
+      if (i == j) then
+        overlap(i,i) = u_dot_u(psi_coefs_inout(1,i),n)
+      else
+        overlap(i,j) = u_dot_v(psi_coefs_inout(1,j),psi_coefs_inout(1,i),n)
+        overlap(j,i) = overlap(i,j)
+      endif
     enddo
   enddo
+  !$OMP END PARALLEL
  print*,'Overlap matrix in the basis of the states considered'
  do i = 1, nstates
   write(*,'(10(F16.10,X))')overlap(i,:)
@@ -315,13 +321,19 @@ subroutine diagonalize_s2_betweenstates(keys_tmp,psi_coefs_inout,n,nmax_keys,nma
  call ortho_lowdin(overlap,size(overlap,1),nstates,psi_coefs_inout,size(psi_coefs_inout,1),n)
  print*,'passed ortho'
 
+ !$OMP PARALLEL DO COLLAPSE(2) DEFAULT(NONE) &
+ !$OMP  PRIVATE(i,j) SHARED(overlap,psi_coefs_inout,nstates,n)
   do i = 1, nstates
-    overlap(i,i) = u_dot_u(psi_coefs_inout(1,i),n)
     do j = i+1, nstates
-      overlap(i,j) = u_dot_v(psi_coefs_inout(1,j),psi_coefs_inout(1,i),n)
-      overlap(j,i) = overlap(i,j)
+      if (i == j) then
+        overlap(i,i) = u_dot_u(psi_coefs_inout(1,i),n)
+      else
+        overlap(i,j) = u_dot_v(psi_coefs_inout(1,j),psi_coefs_inout(1,i),n)
+        overlap(j,i) = overlap(i,j)
+      endif
     enddo
   enddo
+  !$OMP END PARALLEL
  print*,'Overlap matrix in the basis of the Lowdin orthonormalized states '
  do i = 1, nstates
   write(*,'(10(F16.10,X))')overlap(i,:)