orca: emit aux basis and CABS in a %basis block

The ! simple-input line accepts only the orbital basis; putting AuxC/CABS
there is invalid ORCA syntax and broke DLPNO-CCSD(T)-F12 sp jobs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: alongd

arc/job/adapters/orca.py

@@ -92,9 +92,9 @@ def _format_orca_basis(basis: str) -> str:
 # job_options_keywords: input keywords that control the job
 # method_class: 'HF' for wavefunction methods (hf, mp, cc, dlpno ...). 'KS' for DFT methods.
 # options: additional keywords to control job (e.g., TightSCF, NormalPNO ...)
-input_template = """!${restricted}${method_class} ${method} ${basis} ${auxiliary_basis}${cabs} ${keywords}
-!${job_type_1} 
-${job_type_2}
+input_template = """!${restricted}${method_class} ${method} ${basis} ${keywords}
+!${job_type_1}
+${job_type_2}${basis_block}
 %%maxcore ${memory}
 %%pal nprocs ${cpus} end
 
@@ -270,9 +270,19 @@ def write_input_file(self) -> None:
                     'keywords',
                     ]:
             input_dict[key] = ''
-        input_dict['auxiliary_basis'] = _format_orca_basis(self.level.auxiliary_basis or '')
         input_dict['basis'] = _format_orca_basis(self.level.basis or '')
-        input_dict['cabs'] = f' {_format_orca_basis(self.level.cabs)}' if self.level.cabs else ''
+        # In ORCA, the orbital basis is the only basis allowed on the `!` simple-input line.
+        # Auxiliary fitting bases (AuxC) and the F12 CABS must be declared inside a %basis block,
+        # otherwise ORCA raises "UNRECOGNIZED OR DUPLICATED KEYWORD(S) IN SIMPLE INPUT LINE".
+        basis_block_lines = []
+        auxiliary_basis = _format_orca_basis(self.level.auxiliary_basis or '')
+        if auxiliary_basis:
+            basis_block_lines.append(f'AuxC "{auxiliary_basis}"')
+        cabs = _format_orca_basis(self.level.cabs) if self.level.cabs else ''
+        if cabs:
+            basis_block_lines.append(f'CABS "{cabs}"')
+        input_dict['basis_block'] = '\n%basis\n' + '\n'.join(basis_block_lines) + '\nend\n' \
+            if basis_block_lines else ''
         input_dict['charge'] = self.charge
         input_dict['cpus'] = self.cpu_cores
         input_dict['label'] = self.species_label

arc/job/adapters/orca_test.py

@@ -104,8 +104,12 @@ def test_write_input_file(self):
         self.job_1.write_input_file()
         with open(os.path.join(self.job_1.local_path, input_filenames[self.job_1.job_adapter]), 'r') as f:
             content_1 = f.read()
-        job_1_expected_input_file = """!uHF dlpno-ccsd(t) def2-tzvp def2-tzvp/c tightscf normalpno
-!sp 
+        job_1_expected_input_file = """!uHF dlpno-ccsd(t) def2-tzvp tightscf normalpno
+!sp
+
+%basis
+AuxC "def2-tzvp/c"
+end
 
 %maxcore 1792
 %pal nprocs 8 end
@@ -130,8 +134,12 @@ def test_write_input_file_with_SMD_solvation(self):
         self.job_2.write_input_file()
         with open(os.path.join(self.job_2.local_path, input_filenames[self.job_2.job_adapter]), 'r') as f:
             content_2 = f.read()
-        job_2_expected_input_file = """!uHF dlpno-ccsd(t) def2-tzvp def2-tzvp/c tightscf normalpno
-!sp 
+        job_2_expected_input_file = """!uHF dlpno-ccsd(t) def2-tzvp tightscf normalpno
+!sp
+
+%basis
+AuxC "def2-tzvp/c"
+end
 
 %maxcore 1792
 %pal nprocs 8 end
@@ -163,8 +171,12 @@ def test_write_input_file_with_CPCM_solvation(self):
         self.job_3.write_input_file()
         with open(os.path.join(self.job_3.local_path, input_filenames[self.job_3.job_adapter]), 'r') as f:
             content_3 = f.read()
-        job_3_expected_input_file = """!uHF dlpno-ccsd(t) def2-tzvp def2-tzvp/c tightscf normalpno
-!sp 
+        job_3_expected_input_file = """!uHF dlpno-ccsd(t) def2-tzvp tightscf normalpno
+!sp
+
+%basis
+AuxC "def2-tzvp/c"
+end
 
 %maxcore 1792
 %pal nprocs 8 end
@@ -189,7 +201,7 @@ def test_write_input_file_with_CPCM_solvation(self):
         self.assertEqual(content_3, job_3_expected_input_file)
 
     def test_write_input_file_f12_with_cabs(self):
-        """F12 sp_level with a cabs basis emits the CABS token on the ! line."""
+        """F12 sp_level with a cabs basis emits the AuxC and CABS tokens in a %basis block."""
         job_f12 = OrcaAdapter(execution_type='queue',
                               job_type='sp',
                               level=Level(method='DLPNO-CCSD(T)-F12',
@@ -208,8 +220,13 @@ def test_write_input_file_f12_with_cabs(self):
         bang_line = content.splitlines()[0]
         self.assertIn('dlpno-ccsd(t)-f12', bang_line)
         self.assertIn('cc-pvtz-f12', bang_line)
-        self.assertIn('aug-cc-pvtz/c', bang_line)
-        self.assertIn('cc-pvtz-f12-cabs', bang_line)
+        # Aux and CABS must NOT be on the ! line (ORCA rejects them there), only the orbital basis.
+        self.assertNotIn('aug-cc-pvtz/c', bang_line)
+        self.assertNotIn('cabs', bang_line.lower())
+        # They must appear inside a %basis block instead.
+        self.assertIn('%basis', content)
+        self.assertIn('AuxC "aug-cc-pvtz/c"', content)
+        self.assertIn('CABS "cc-pvtz-f12-cabs"', content)
 
     def test_write_input_file_f12_without_cabs_raises(self):
         """F12 sp_level without a cabs basis raises at input-file generation."""