Support for edge case of structures with all isolated atoms

chgnet/model/model.py

@@ -818,6 +818,9 @@ def from_graphs(
 
             # Bonds
             atom_cart_coords = graph.atom_frac_coord @ lattice
+            if graph.atom_graph.dim() == 1:
+                # This is to avoid structure with all atoms isolated
+                graph.atom_graph = graph.atom_graph.reshape(0, 2)
             bond_basis_ag, bond_basis_bg, bond_vectors = bond_basis_expansion(
                 center=atom_cart_coords[graph.atom_graph[:, 0]],
                 neighbor=atom_cart_coords[graph.atom_graph[:, 1]],

tests/test_model.py

@@ -4,7 +4,7 @@
 
 import numpy as np
 import pytest
-from pymatgen.core import Structure
+from pymatgen.core import Lattice, Structure
 
 from chgnet import ROOT
 from chgnet.graph import CrystalGraphConverter
@@ -207,6 +207,18 @@ def test_predict_batched_structures() -> None:
             )
 
 
+def test_predict_isolated_structures() -> None:
+    lattice10 = Lattice.cubic(10)
+    lattice20 = Lattice.cubic(20)
+    positions = [[0, 0, 0], [0.5, 0.5, 0.5]]
+
+    # Create the structure
+    model.graph_converter.set_isolated_atom_response("ignore")
+    prediction10 = model.predict_structure(Structure(lattice10, ["H", "H"], positions))
+    prediction20 = model.predict_structure(Structure(lattice20, ["H", "H"], positions))
+    assert prediction10["e"] == pytest.approx(prediction20["e"], rel=1e-5, abs=1e-5)
+
+
 def test_as_to_from_dict() -> None:
     dct = model.as_dict()
     assert {*dct} == {"model_args", "state_dict"}