diff --git a/run_hartree_fock.ml b/run_hartree_fock.ml
index 687fc0b..2a9f8df 100644
--- a/run_hartree_fock.ml
+++ b/run_hartree_fock.ml
@@ -54,7 +54,7 @@ let () =
 
   let guess = 
     match Command_line.get "guess" with
-    | None -> `Hcore
+    | None -> `Huckel
     | Some filename ->
       let s_guess = Simulation.of_filenames
           ~charge ~multiplicity ~nuclei:nuclei_file filename in