Fix surface phase loading in Cantera model converter

Load surface phase name dynamically from generated YAML instead of
assuming hardcoded 'surface1'. This makes the code compatible with
different CHEMKIN surface file specifications that may define
different phase names (e.g., SURF0).

Fixes failing tests in canteramodelTest.py.

Author: rwest

rmgpy/tools/canteramodel.py

@@ -341,6 +341,7 @@ def load_chemkin_model(self, chemkin_file, transport_file=None, **kwargs):
         Note that if this is a surface mechanism, the calling function much include surface_file as a keyword argument for the parser
         """
         from cantera import ck2yaml
+        import yaml
 
         base = os.path.basename(chemkin_file)
         base_name = os.path.splitext(base)[0]
@@ -353,7 +354,20 @@ def load_chemkin_model(self, chemkin_file, transport_file=None, **kwargs):
         self.model = ct.Solution(out_name)
 
         if self.surface:
-            self.surface = ct.Interface(out_name, 'surface1')
+            # Find the surface phase name in the generated YAML file
+            with open(out_name, 'r') as f:
+                yaml_data = yaml.safe_load(f)
+            
+            surface_phase_name = None
+            for phase in yaml_data.get('phases', []):
+                if phase.get('thermo') == 'ideal-surface':
+                    surface_phase_name = phase.get('name')
+                    break
+            
+            if surface_phase_name is None:
+                raise ValueError(f"No surface phase found in {out_name}")
+            
+            self.surface = ct.Interface(out_name, surface_phase_name)
             self.model = self.surface.adjacent['gas']
 
     def modify_reaction_kinetics(self, rmg_reaction_index, rmg_reaction):