diff --git a/examples/thermoEstimator/input.py b/examples/thermoEstimator/input.py
index 6f1bb29a48..dcb3bb7275 100644
--- a/examples/thermoEstimator/input.py
+++ b/examples/thermoEstimator/input.py
@@ -25,6 +25,7 @@
 
 quantumMechanics(
     software='mopac',
+    method='pm3',
     fileStore='QMfiles', # relative to where you run it? defaults to inside the output folder.
     scratchDirectory = None, # not currently used
     onlyCyclics = True,