diff --git a/blueprints/operational_chemistry/machine_specific/alcc_spack/batch_preambles/main b/blueprints/operational_chemistry/machine_specific/alcc_spack/batch_preambles/main
index 3371ef8518d10503420e3c066fd61d9bfa698f99..f0507f7f58015fe6d734ac1e8bb20b06c18690d3 100644
--- a/blueprints/operational_chemistry/machine_specific/alcc_spack/batch_preambles/main
+++ b/blueprints/operational_chemistry/machine_specific/alcc_spack/batch_preambles/main
@@ -1,5 +1,5 @@
 #!/bin/bash -l
-#SBATCH --partition=alcc1,epyc
+#SBATCH --partition=epyc
 #SBATCH -o __runDir__/__mainJobName__.%j.%N.out
 #SBATCH -D __runDir__
 #SBATCH -J __mainJobName__
diff --git a/blueprints/operational_chemistry/machine_specific/alcc_spack/config.bash b/blueprints/operational_chemistry/machine_specific/alcc_spack/config.bash
index 4d9278078b7260e9b0c40e6d8031dd556117994c..8febf3bf9c3bdf5dd7a7ba6bae5a443b60e4b7f0 100644
--- a/blueprints/operational_chemistry/machine_specific/alcc_spack/config.bash
+++ b/blueprints/operational_chemistry/machine_specific/alcc_spack/config.bash
@@ -60,7 +60,7 @@ removeRunDir=false
 # --- MPI settings ---
 
 mpiCommandPre="mpirun /usr/bin/time -v"
-mpiCommandMain="mpirun /usr/bin/time -v"
+mpiCommandMain="mpirun -mca pml ucx -mca coll ^hcoll -x UCX_TLS=tcp,shm -x UCX_NET_DEVICES=eth5 /usr/bin/time -v"
 mpiCommandReal=${mpiCommandPre}
 
 # --- Batch system ---