diff --git a/docs/source/users_guide/qp_export_as_tgz.rst b/docs/source/users_guide/qp_export_as_tgz.rst
new file mode 100644
index 00000000..1333ed77
--- /dev/null
+++ b/docs/source/users_guide/qp_export_as_tgz.rst
@@ -0,0 +1 @@
+TODO
diff --git a/scripts/qp_export_as_tgz.sh b/scripts/qp_export_as_tgz
similarity index 60%
rename from scripts/qp_export_as_tgz.sh
rename to scripts/qp_export_as_tgz
index 8fd3e40e..72371ef6 100755
--- a/scripts/qp_export_as_tgz.sh
+++ b/scripts/qp_export_as_tgz
@@ -2,7 +2,7 @@
 # 
 # Creates a self-contained binary distribution in the form of a tar.gz file
 # 
-# Tue Jan 13 14:06:25 CET 2015
+# Mon Nov 26 22:57:50 CET 2018
 #
 
 
@@ -20,14 +20,10 @@ if [[ -f quantum_package.rc \
    && -d src  \
    && -d bin  \
    && -d ocaml \
+   && -d external \
    && -d scripts ]]
 then
-  head -1 README.md | grep "IMPORTANT" > /dev/null
-  if [[ $? -ne 0 ]]
-  then
-    echo "This doesn't look like a quantum_package directory  (README.md)"
-    exit 1
-  fi
+  : # OK, this is a quantum_package directory
 else
   echo "This doesn't look like a quantum_package directory"
   exit 1
@@ -65,10 +61,10 @@ echo "Creating root of static directory"
 #     ---------------------------------
 
 rm -rf -- ${QPACKAGE_STATIC}
-mkdir -p -- ${QPACKAGE_STATIC}/{bin,lib,extra_lib,install}
+mkdir -p -- ${QPACKAGE_STATIC}/{bin,lib,extra_lib,external}
 if [[ $? -ne 0 ]] ;
 then
-  echo "Error creating ${QPACKAGE_STATIC}/{bin,lib,extra_lib,install}"
+  echo "Error creating ${QPACKAGE_STATIC}/{bin,lib,extra_lib,external}"
   exit 1
 fi
 
@@ -140,18 +136,6 @@ fi
 
 cp -- ${QPACKAGE_STATIC}/extra_lib/lib{[gi]omp*,mkl*,lapack*,blas*,z*} ${QPACKAGE_STATIC}/lib/
 
-#
-echo "Copying EMSL_Basis directory"
-#     ---------------------------- 
-
-cp -r -- ${QP_ROOT}/install/emsl ${QPACKAGE_STATIC}/install
-if [[ $? -ne 0 ]] ;
-then
-  echo 'cp -r -- ${QP_ROOT}/install/emsl ${QPACKAGE_STATIC}/'
-  exit 1
-fi
-
-
 #
 echo "Copying scripts directory"
 #     ------------------------- 
@@ -162,37 +146,29 @@ then
   echo 'cp -r -- ${QP_ROOT}/scripts ${QPACKAGE_STATIC}/'
   exit 1
 fi
-cp ${QP_ROOT}/install/EZFIO/Python/ezfio.py ${QPACKAGE_STATIC}/scripts/
+#
+
+echo "Copying external libraries"
+#     --------------------------
+
+cp -r -- ${QP_ROOT}/external/emsl ${QPACKAGE_STATIC}/external
+if [[ $? -ne 0 ]] ;
+then
+  echo 'cp -r -- ${QP_ROOT}/external/emsl ${QPACKAGE_STATIC}/'
+  exit 1
+fi
+
+cp -r ${QP_ROOT}/external/Python ${QPACKAGE_STATIC}/external/
+mkdir ${QPACKAGE_STATIC}/external/ezfio
+cp -r ${QP_ROOT}/external/ezfio/Python ${QPACKAGE_STATIC}/external/ezfio/
+cp -r ${QP_ROOT}/external/ezfio/Bash   ${QPACKAGE_STATIC}/external/ezfio/
 
 
 #
 echo "Creating quantum_package.rc"
 #     ---------------------------
 
-cat << EOF > ${QPACKAGE_STATIC}/quantum_package.rc
-export QP_ROOT=\$( cd \$(dirname "\${BASH_SOURCE}")  ; pwd -P )
-
-export QP_EZFIO=\${QP_ROOT}/install/EZFIO
-export QP_PYTHON=\${QP_ROOT}/scripts:\${QP_ROOT}/scripts/ezfio_interface:\${QP_ROOT}/scripts/utility:\${QP_ROOT}/scripts/module:\${QP_ROOT}/scripts/pseudo:\${QP_ROOT}/scripts/compilation:\${QP_ROOT}/install/bats:\${QP_ROOT}/install/Downloads:\${QP_ROOT}/install/eigen:\${QP_ROOT}/install/p_graphviz:\${QP_ROOT}/install/gmp:\${QP_ROOT}/install/resultsFile:\${QP_ROOT}/install/_build:\${QP_ROOT}/install/emsl:\${QP_ROOT}/install/scripts:\${QP_ROOT}/install/docopt:\${QP_ROOT}/install/irpf90:\${QP_ROOT}/install/zlib:\${QP_ROOT}/install/EZFIO
-
-export IRPF90=\${QP_ROOT}/bin/irpf90
-export NINJA=\${QP_ROOT}/bin/ninja
-function qp_prepend_export () {
-eval "value_1="\\\${\$1}""
-if [[ -z \$value_1 ]] ; then
-    echo "\${2}:"
-else
-    echo "\${2}:\${value_1}"
-fi
-}
-export PYTHONPATH=\$(qp_prepend_export "PYTHONPATH" "\${QP_EZFIO}/Python":"\${QP_PYTHON}")
-export PATH=\$(qp_prepend_export "PATH" "\${QP_PYTHON}":"\${QP_ROOT}"/bin:"\${QP_ROOT}"/ocaml)
-export LD_LIBRARY_PATH=\$(qp_prepend_export "LD_LIBRARY_PATH" "\${QP_ROOT}"/lib:"\${QP_ROOT}"/extra_lib:"\${QP_ROOT}"/lib64)
-export LIBRARY_PATH=\$(qp_prepend_export "LIBRARY_PATH" "\${QP_ROOT}"/lib:"\${QP_ROOT}"/extra_lib:"\${QP_ROOT}"/lib64)
-export C_INCLUDE_PATH=\$(qp_prepend_export "C_INCLUDE_PATH" "\${QP_ROOT}"/include)
-
-# export QP_NIC=ib0
-EOF
+sed "s!^export QP_ROOT=.*\$!export QP_ROOT=\$( cd \$(dirname "\${BASH_SOURCE}")  ; pwd -P )!" ${QP_ROOT}/quantum_package.rc.default > ${QPACKAGE_STATIC}/quantum_package.rc
 
 #exit 0
 #
diff --git a/scripts/qp_mpirun b/scripts/qp_mpirun
new file mode 100755
index 00000000..0ace9b35
--- /dev/null
+++ b/scripts/qp_mpirun
@@ -0,0 +1,85 @@
+#!/bin/bash
+
+set -e 
+
+NODES=($(mpirun hostname))
+
+# Test that there is one MPI process per node
+NPROC=$(echo ${NODES[@]} | tr ' ' '\n' | sort | wc -l)
+NUNIQ=$(echo ${NODES[@]} | tr ' ' '\n' | sort | uniq | wc -l)
+if [[ $NPROC != $NUNIQ ]]
+then
+        echo "
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Error:
+
+There are more than one process per host.
+In your SLURM script file, use:
+
+   #SBATCH --nodes=$NPROC
+   #SBATCH --ntasks-per-node=1
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+        "
+        exit -1
+fi
+
+PROG=$1
+INPUT=$2
+
+# Check if quantum_package.rc is sourced
+
+if [[ -z ${QP_ROOT} ]]
+then
+        echo "Error: quantum_package.rc is not sourced"
+        exit -1
+fi
+
+
+# Get host names
+
+MASTER_NODE=${NODES[0]}
+SLAVE_NODES=$(echo ${NODES[@]:1}| tr ' ' ',')
+if [[ $NPROC -gt 1 ]]
+then
+    echo "Master : $MASTER_NODE"
+    echo "Slaves : $SLAVE_NODES"
+fi
+
+# Check if the integrals can be read
+source ${QP_ROOT}/external/ezfio/Bash/ezfio.sh
+ezfio set_file $INPUT
+RW=$(ezfio get integrals_bielec disk_access_mo_integrals)
+if [[ $RW != Read ]]
+then
+  echo "
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Warning:
+
+Two-electron integrals were not saved to disk in a previous run.
+If the 4-index transformation takes time, you may consider 
+killing this job and running 
+
+    qp_run Four_idx_transform $INPUT
+
+as a single-node job before re-submitting the current job.
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+"
+fi
+rm -f $INPUT/work/qp_run_address
+set -x
+mpiexec.hydra -n 1 -hosts "$MASTER_NODE" qp_run $PROG $INPUT &
+
+if [[ $NPROC -gt 1 ]]
+then
+    while [[ ! -f $INPUT/work/qp_run_address ]]
+    do
+        sleep 1
+    done
+    echo "Starting slaves"
+    mpiexec.hydra -n $((${SLURM_NTASKS}-1)) -hosts "$SLAVE_NODES" qp_run -slave slave_cipsi $INPUT > $INPUT.slaves.out
+fi
+wait
+
+
diff --git a/scripts/qp_srun b/scripts/qp_srun
new file mode 100755
index 00000000..5c7847de
--- /dev/null
+++ b/scripts/qp_srun
@@ -0,0 +1,85 @@
+#!/bin/bash
+
+set -e 
+
+NODES=($(srun hostname))
+
+# Test that there is one MPI process per node
+NPROC=$(echo ${NODES[@]} | tr ' ' '\n' | sort | wc -l)
+NUNIQ=$(echo ${NODES[@]} | tr ' ' '\n' | sort | uniq | wc -l)
+if [[ $NPROC != $NUNIQ ]]
+then
+        echo "
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Error:
+
+There are more than one process per host.
+In your SLURM script file, use:
+
+   #SBATCH --nodes=$NPROC
+   #SBATCH --ntasks-per-node=1
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+        "
+        exit -1
+fi
+
+PROG=$1
+INPUT=$2
+
+# Check if quantum_package.rc is sourced
+
+if [[ -z ${QP_ROOT} ]]
+then
+        echo "Error: quantum_package.rc is not sourced"
+        exit -1
+fi
+
+
+# Get host names
+
+MASTER_NODE=${NODES[0]}
+SLAVE_NODES=$(echo ${NODES[@]:1}| tr ' ' ',')
+if [[ $NPROC -gt 1 ]]
+then
+    echo "Master : $MASTER_NODE"
+    echo "Slaves : $SLAVE_NODES"
+fi
+
+# Check if the integrals can be read
+source ${QP_ROOT}/external/ezfio/Bash/ezfio.sh
+ezfio set_file $INPUT
+RW=$(ezfio get integrals_bielec disk_access_mo_integrals)
+if [[ $RW != Read ]]
+then
+  echo "
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Warning:
+
+Two-electron integrals were not saved to disk in a previous run.
+If the 4-index transformation takes time, you may consider 
+killing this job and running 
+
+    qp_run Four_idx_transform $INPUT
+
+as a single-node job before re-submitting the current job.
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+"
+fi
+rm -f $INPUT/work/qp_run_address
+set -x
+srun -n 1 qp_run $PROG $INPUT &
+
+if [[ $NPROC -gt 1 ]]
+then
+    while [[ ! -f $INPUT/work/qp_run_address ]]
+    do
+        sleep 1
+    done
+    echo "Starting slaves"
+    srun -n $((${SLURM_NTASKS}-1)) qp_run -slave slave_cipsi $INPUT > $INPUT.slaves.out
+fi
+wait
+
+
diff --git a/src/Davidson/EZFIO.cfg b/src/Davidson/EZFIO.cfg
index b1b5d013..5beadf2f 100644
--- a/src/Davidson/EZFIO.cfg
+++ b/src/Davidson/EZFIO.cfg
@@ -34,3 +34,9 @@ doc: If |true|, use the distributed algorithm
 default: True 
 interface: ezfio,provider,ocaml
 
+[only_expected_s2]
+type: logical
+doc: If |true|, use filter out all vectors with bad |S^2| values
+default: True
+interface: ezfio,provider,ocaml
+
diff --git a/src/Davidson/diagonalization_hs2_dressed.irp.f b/src/Davidson/diagonalization_hs2_dressed.irp.f
index d1c52426..1d2f3d7a 100644
--- a/src/Davidson/diagonalization_hs2_dressed.irp.f
+++ b/src/Davidson/diagonalization_hs2_dressed.irp.f
@@ -404,7 +404,7 @@ subroutine davidson_diag_hjj_sjj(dets_in,u_in,H_jj,s2_out,energies,dim_in,sze,N_
         s2(k) = s_(k,k) + S_z2_Sz
       enddo
 
-      if (s2_eig) then
+      if (only_expected_s2) then
           do k=1,shift2
             state_ok(k) = (dabs(s2(k)-expected_s2) < 0.6d0)
           enddo
diff --git a/src/FCI/zmq_selection.irp.f b/src/FCI/zmq_selection.irp.f
index 6d8ee443..ff1a0f0d 100644
--- a/src/FCI/zmq_selection.irp.f
+++ b/src/FCI/zmq_selection.irp.f
@@ -121,7 +121,7 @@ subroutine ZMQ_selection(N_in, pt2, variance, norm)
     norm(i) = 0.d0
   enddo
   if (N_in > 0) then
-    if (s2_eig.or.(N_states > 1) ) then
+    if (s2_eig) then
       call make_selection_buffer_s2(b)
     endif
     call fill_H_apply_buffer_no_selection(b%cur,b%det,N_int,0)