Add a edge case test that computes int1e with fakemol, that supposes …

…to fail

gpu4pyscf/df/tests/test_int3c2e.py

@@ -14,10 +14,11 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import pyscf
-from pyscf import df
+from pyscf import df, gto
 from pyscf.gto.moleintor import getints, make_cintopt
 from pyscf.df.grad.rhf import _int3c_wrapper
 import numpy as np
+import cupy as cp
 import unittest
 from gpu4pyscf.df import int3c2e
 from gpu4pyscf.lib.cupy_helper import load_library
@@ -147,6 +148,46 @@ def test_int1e_iprinvip(self):
             h1ao = mol.intor('int1e_iprinvip', comp=9) # <\nabla|1/r|>
             assert np.linalg.norm(int3c[:,:,:,i] - h1ao) < 1e-7
 
+    def test_int1e_edge_case(self):
+        mol = gto.M(
+            atom =
+            """
+            H 0 0 0
+            H -1 0.0 0
+            """,
+            basis =
+            """
+            H    S
+                0.1612777588       1.0000000
+            """)
+        mol.build()
+
+        xs = np.arange(-3.01, 3.00, 5.0)
+        ys = np.arange(-3.02, 3.00, 10.0)
+        zs = np.arange(-3.03, 3.00, 10.0)
+        grid_points = pyscf.lib.cartesian_prod([xs, ys, zs])
+
+        nao = mol.nao
+        ngrids = grid_points.shape[0]
+        dm = np.ones((nao, nao))
+        charges = np.ones(ngrids)
+
+        int3c2e_ip2 = mol._add_suffix('int3c2e_ip2')
+        cintopt = gto.moleintor.make_cintopt(mol._atm, mol._bas, mol._env, int3c2e_ip2)
+        fakemol = gto.fakemol_for_charges(grid_points)
+        q_nj = df.incore.aux_e2(mol, fakemol, intor=int3c2e_ip2, aosym='s1', cintopt=cintopt)
+        dq_cpu = np.einsum('xijk,ij,k->xk', q_nj, dm, charges)
+
+        dm = cp.asarray(dm)
+        charges = cp.asarray(charges)
+        intopt = int3c2e.VHFOpt(mol, fakemol, 'int2e')
+        intopt.build(1e-14, diag_block_with_triu=True, aosym=False)
+        coeff = intopt.coeff
+        dm_cart = coeff @ dm @ coeff.T
+        dq_gpu, _ = int3c2e.get_int3c2e_ip_jk(intopt, 0, 'ip2', charges, None, dm_cart)
+
+        cp.testing.assert_allclose(dq_cpu, dq_gpu, atol = 1e-10)
+
 if __name__ == "__main__":
     print("Full Tests for int3c")
     unittest.main()