Don't call a subprocess with VASP custodian (#1850)

## Summary of Changes

Call Custodian directly rather than via a subprocess for VASP.

FYI: @zulissimeta, I had to revert this PR due to issues with concurrent
calculations in certain workflow engines. Once we solve the upstream
issue in Custodian, I can re-merge this PR.

Requires:
- #1821
- Custodian > 2024.2.15

### Checklist

- [X] I have read the ["Guidelines"
section](https://quantum-accelerators.github.io/quacc/dev/contributing.html#guidelines)
of the contributing guide. Don't lie! 😉
- [X] My PR is on a custom branch and is _not_ named `main`.
- [X] I have added relevant, comprehensive [unit
tests](https://quantum-accelerators.github.io/quacc/dev/contributing.html#unit-tests).

### Notes

- Your PR will likely not be merged without proper and thorough tests.
- If you are an external contributor, you will see a comment from
[@buildbot-princeton](https://github.com/buildbot-princeton). This is
solely for the maintainers.
- When your code is ready for review, ping one of the [active
maintainers](https://quantum-accelerators.github.io/quacc/about/contributors.html#active-maintainers).

src/quacc/calculators/vasp/vasp.py

@@ -2,9 +2,8 @@
 
 from __future__ import annotations
 
-import inspect
 import os
-import sys
+import subprocess
 from pathlib import Path
 from typing import TYPE_CHECKING
 
@@ -13,7 +12,6 @@
 from ase.calculators.vasp import setups as ase_setups
 from ase.constraints import FixAtoms
 
-from quacc.calculators.vasp import vasp_custodian
 from quacc.calculators.vasp.io import load_vasp_yaml_calc
 from quacc.calculators.vasp.params import (
     get_param_swaps,
@@ -23,6 +21,7 @@
     set_auto_dipole,
     set_pmg_kpts,
 )
+from quacc.calculators.vasp.vasp_custodian import run_custodian
 from quacc.schemas.prep import set_magmoms
 from quacc.utils.dicts import sort_dict
 
@@ -181,10 +180,6 @@ def _manage_environment(self) -> str:
                 "VASP_VDW setting was not provided, yet you requested a vdW functional."
             )
 
-        if self.use_custodian:
-            run_vasp_custodian_file = Path(inspect.getfile(vasp_custodian)).resolve()
-            return f"{sys.executable} {run_vasp_custodian_file}"
-
         # Return vanilla ASE command
         vasp_cmd = (
             SETTINGS.VASP_GAMMA_CMD
@@ -290,3 +285,39 @@ def _cleanup_params(self) -> None:
         self.user_calc_params = sort_dict(
             normalize_params(remove_unused_flags(self.user_calc_params))
         )
+
+    def _run(
+        self,
+        command: list[str] | None = None,
+        out: Path | str | None = None,
+        directory: Path | str | None = None,
+    ) -> int:
+        """
+        Override the Vasp calculator's run method to use Custodian if necessary.
+
+        Parameters
+        ----------
+        command
+            The command to run the VASP calculation. If None, will use the
+            self.command attribute.
+        out
+            The stdout file path.
+        directory
+            The directory to run the calculation in. If None, will use the
+            self.directory attribute.
+
+        Returns
+        -------
+        int
+            The return code.
+        """
+        if command is None:
+            command = self.command
+        if directory is None:
+            directory = self.directory
+
+        if self.use_custodian:
+            run_custodian(directory=directory)
+            return 0
+        else:
+            return subprocess.call(command, shell=True, stdout=out, cwd=directory)

src/quacc/calculators/vasp/vasp_custodian.py

@@ -68,6 +68,7 @@ def run_custodian(
     vasp_custodian_handlers: list[str] | None = None,
     vasp_custodian_validators: list[str] | None = None,
     scratch_dir: str | None = None,
+    directory: str | None = "./",
     vasp_job_kwargs: VaspJobKwargs | None = None,
     custodian_kwargs: CustodianKwargs | None = None,
 ) -> list[list[dict]]:
@@ -202,6 +203,7 @@ def run_custodian(
         validators=validators,
         max_errors=vasp_custodian_max_errors,
         scratch_dir=scratch_dir,
+        directory=directory,
         **custodian_kwargs,
     )
 

tests/core/calculators/vasp/test_vasp.py

@@ -903,3 +903,8 @@ def test_run(monkeypatch, tmp_path):
     atoms = bulk("Cu")
     calc = Vasp(atoms, xc="PBE", use_custodian=False)
     assert calc._run() > 0
+
+    atoms = bulk("Cu")
+    calc = Vasp(atoms, xc="PBE", use_custodian=True)
+    with pytest.raises(FileNotFoundError):
+        calc._run()