Parse only POTCAR metadata from OUTCAR when supplementing vasprun.xml

When vasprun.xml is the mainfile, OUTCAR now only supplements pseudopotential
metadata (SHA256, LPAW, LULTRA, ENMAX, etc.) instead of parsing all data.
This avoids redundant parsing since vasprun.xml already contains eigenvalues,
energies, and forces.

Changes:
- Create minimal `outcar_supplement_parser` with only pseudopotential quantity
- Fix POTCAR regex to require VRHFIN within matched content, not just ahead:
  `POTCAR:([\s\S]+?VRHFIN[\s\S]+?)(?=\s*POTCAR:|\s*local pseudopotential:|\Z)`
  This prevents matching header-only POTCAR lines that lack detailed metadata
- Simplify `_find_outcar()` to use generator expression with `next()`
- Update comments to reflect POTCAR-specific scope

Fixes issue where 4 pseudopotentials were parsed instead of 2 due to regex
matching both header-only lines and detailed sections.

Author: ndaelman-hu

src/nomad_simulation_parsers/parsers/vasp/outcar_parser.py

@@ -336,7 +336,7 @@ def str_to_eigenvalues(val_in):
             ),
             Quantity(
                 'pseudopotentials',
-                r'POTCAR:(?=[\s\S]*?VRHFIN)([\s\S]+?)(?=\s*$|\s*POTCAR:|\s*local pseudopotential:)',
+                r'POTCAR:([\s\S]+?VRHFIN[\s\S]+?)(?=\s*POTCAR:|\s*local pseudopotential:|\Z)',
                 repeats=True,
                 sub_parser=TextParser(quantities=potcar_quantities),
             ),

src/nomad_simulation_parsers/parsers/vasp/xml_parser.py

@@ -92,23 +92,36 @@ def write_to_archive(self) -> None:
         data_parser.annotation_key = vasp.XML2_KEY
         xml_parser.convert(data_parser)
 
-        # Third pass: OUTCAR_KEY to extend with OUTCAR data if available
+        # Third pass: OUTCAR_KEY to extend with OUTCAR pseudopotential metadata
         # This allows OUTCAR to supplement vasprun.xml pseudopotentials with
-        # detailed metadata
+        # detailed metadata (SHA256, LPAW, LULTRA, etc.)
         outcar_path = self._find_outcar()
         if outcar_path and os.path.exists(outcar_path):
             LOGGER.info(
-                f'Found OUTCAR at {outcar_path}, extending vasprun.xml data '
-                'with detailed pseudopotential metadata'
+                f'Found OUTCAR at {outcar_path}, extending vasprun.xml pseudopotentials '
+                'with detailed metadata'
+            )
+            from nomad.parsing.file_parser import Quantity, TextParser
+            from nomad.parsing.file_parser.mapping_parser import (
+                TextParser as MappingTextParser,
             )
             from nomad_simulation_parsers.parsers.vasp.outcar_parser import (
-                OutcarParser,
-                OutcarTextParser,
+                potcar_quantities,
+            )
+
+            outcar_supplement_parser = TextParser(
+                quantities=[
+                    Quantity(
+                        'pseudopotentials',
+                        r'POTCAR:([\s\S]+?VRHFIN[\s\S]+?)(?=\s*POTCAR:|\s*local pseudopotential:|\Z)',
+                        repeats=True,
+                        sub_parser=TextParser(quantities=potcar_quantities),
+                    )
+                ]
             )
 
-            outcar_parser = OutcarParser()
-            outcar_parser.text_parser = OutcarTextParser()
-            outcar_parser.filepath = outcar_path
+            outcar_parser = MappingTextParser(filepath=outcar_path)
+            outcar_parser.text_parser = outcar_supplement_parser
 
             data_parser.annotation_key = vasp.OUTCAR_KEY
             # Merge by index position: OUTCAR PP[0] extends XML PP[0], etc.
@@ -124,13 +137,13 @@ def write_to_archive(self) -> None:
         xml_parser.close()
 
     def _find_outcar(self) -> str | None:
-        """Find OUTCAR file in the same directory as vasprun.xml."""
-        mainfile_dir = PathLib(self.mainfile).parent
+        """Find OUTCAR file in the same directory as vasprun.xml.
 
-        # Check for any file starting with 'outcar' (case-insensitive)
-        # Catches: OUTCAR, outcar, OUTCAR.gz, outcar.bz2, etc.
-        for file in mainfile_dir.iterdir():
-            if file.name.lower().startswith('outcar'):
-                return str(file)
-
-        return None
+        Matches any file starting with 'outcar' (case-insensitive):
+        OUTCAR, outcar, OUTCAR.gz, outcar.bz2, etc.
+        """
+        mainfile_dir = PathLib(self.mainfile).parent
+        return next(
+            (str(f) for f in mainfile_dir.iterdir() if f.name.lower().startswith('outcar')),
+            None
+        )