Bug fix on two H test when HOMO LUMO are degenerate

Author: henryw7

gpu4pyscf/hessian/rhf.py

@@ -629,6 +629,9 @@ def solve_mo1(mf, mo_energy, mo_coeff, mo_occ, h1mo,
     e_ai = 1 / (e_a[:,None] + level_shift - e_i)
     nvir, nocc = e_ai.shape
 
+    if any(np.isinf(e_ai)) or any(np.isnan(e_ai)):
+        raise ValueError(f"e_ai = {e_ai} contains inf or nan, likely because HOMO-LUMO gap is zero.")
+
     mocc = mo_coeff[:,occidx]
     nao, nmo = mo_coeff.shape
     natm = mol.natm

gpu4pyscf/hessian/tests/test_large_exponent.py

@@ -181,6 +181,7 @@ def test_hessian_large_exp_two_atom_rks(self):
         mf = dft.RKS(mol_minimal_two_atom, xc = "wB97X")
         mf.grids.atom_grid = (50,194)
         mf.conv_tol = 1e-10
+        mf.level_shift = 0.001
 
         mf.kernel()
         assert mf.converged