diff --git a/atomistics/calculators/lammps.py b/atomistics/calculators/lammps.py
index aec31874..65eae009 100644
--- a/atomistics/calculators/lammps.py
+++ b/atomistics/calculators/lammps.py
@@ -61,7 +61,7 @@ def evaluate_with_lammps_library(
     tasks: list[TaskName],
     potential_dataframe: DataFrame,
     lmp: LammpsASELibrary,
-    lmp_optimizer_kwargs: dict,
+    lmp_optimizer_kwargs: dict = {},
 ):
     results = {}
     if "optimize_positions_and_volume" in tasks: