Generate unique entry_id using date time and hash of final structure.

Fixes #4259

src/pymatgen/io/vasp/outputs.py

@@ -11,7 +11,6 @@
 from collections import defaultdict
 from collections.abc import Iterable
 from dataclasses import dataclass
-from datetime import datetime, timezone
 from glob import glob
 from io import StringIO
 from pathlib import Path
@@ -868,7 +867,11 @@ def get_computed_entry(
             ComputedStructureEntry/ComputedEntry
         """
         if entry_id is None:
-            entry_id = f"vasprun-{datetime.now(tz=timezone.utc)}"
+            calc_date = re.sub(" ", "", self.generator["DATE"])
+            calc_time = self.generator["TIME"]
+            hashed_structure = hash(str(self.final_structure))
+
+            entry_id = f"vasprun-{calc_date}-{calc_time}-{hashed_structure}"
         param_names = {
             "is_hubbard",
             "hubbards",

tests/io/vasp/test_outputs.py

@@ -326,7 +326,9 @@ def test_standard(self):
         assert dct["nelements"] == 4
 
         entry = vasp_run.get_computed_entry(inc_structure=True)
-        assert entry.entry_id.startswith("vasprun")
+
+        assert entry.entry_id == "vasprun-20100729-15.0-5360923159595666479"
+
         assert entry.parameters["run_type"] == "PBEO or other Hybrid Functional"
 
     def test_unconverged(self):