Avoid parsing active space when wavefunctions are used without proceeding to MRCI in molpro (#830)

Parsing active space is needed before running an MRCI job in molpro. For
a method type labeled as wavefunction (CC), ARC tries to run
parse_active_space, but stops the whole job if SP was not in molpro.
Fixed to allow using wavefunctions without MRCI.

Author: calvinp0

arc/parser/parser.py

@@ -539,7 +539,7 @@ def parse_active_space(sp_path: str, species: 'ARCSpecies') -> Optional[Dict[str
     if not os.path.isfile(sp_path):
         raise InputError(f'Could not find file {sp_path}')
     if not determine_ess(sp_path) == 'molpro':
-        raise InputError(f'File {sp_path} is not a Molpro output file, cannot parse active space.')
+        return None
     active = dict()
     num_heavy_atoms = sum([1 for symbol in species.get_xyz()['symbols'] if symbol not in ['H', 'D', 'T']])
     nuclear_charge, total_closed_shell_orbitals, total_active_orbitals = None, None, None

arc/scheduler.py

@@ -2681,7 +2681,7 @@ def post_sp_actions(self,
         if self.sp_level is not None and 'ccsd' in self.sp_level.method:
             self.species_dict[label].t1 = parser.parse_t1(self.output[label]['paths']['sp'])
         self.species_dict[label].e_elect = parser.parse_e_elect(self.output[label]['paths']['sp'])
-        if level is not None and level.method_type == 'wavefunction':
+        if level is not None and level.method_type == 'wavefunction' and self.species_dict[label].active is None:
             self.species_dict[label].active = parser.parse_active_space(sp_path=self.output[label]['paths']['sp'],
                                                                         species=self.species_dict[label])
         if self.species_dict[label].t1 is not None: