Fixed PET and rascal drivers (i-pi#310)

* Fixed PET and rascal drivers

drivers/py/pes/pet.py

@@ -27,7 +27,7 @@ class PET_driver(Dummy_driver):
     def __init__(self, args=None, verbose=False):
         self.error_msg = """
 The PET driver requires specification of a .json model file fitted with 
-the PET tools, and a template file that describes the chemical makeup of 
+    the PET tools, and a template file that describes the chemical makeup of 
 the structure. 
 
 Example: python driver.py -m pet -u -o model.json,template.xyz
@@ -43,10 +43,7 @@ def check_arguments(self):
 
         This loads the potential and atoms template in PET
         """
-        try:
-            arglist = self.args.split(",")
-        except ValueError:
-            sys.exit(self.error_msg)
+        arglist = self.args
 
         if len(arglist) == 2:
             self.model_path = arglist[0]

drivers/py/pes/rascal.py

@@ -33,10 +33,7 @@ def check_arguments(self):
 
         This loads the potential and atoms template in librascal
         """
-        try:
-            arglist = self.args
-        except ValueError:
-            sys.exit(self.error_msg)
+        arglist = self.args
 
         if len(arglist) == 2:
             self.model = arglist[0]

examples/clients/pet/README.md

@@ -14,7 +14,15 @@ wget https://zenodo.org/records/10250171/files/methane.pet_small.zip
 unzip methane.pet_small.zip
 ```
 
-After having obtained the potential file, the example can be run as usual
+A version of the PET code that is compatible with this example can be 
+obtained with 
+
+```bash
+pip install git+https://github.com/serfg/pet@83454c6
+```
+
+After having obtained the potential file, and a compatible version of PET,
+the example can be run as usual
 
 ```bash
 i-pi input.xml &> log.ipi &