diff --git a/.coveragerc b/.coveragerc
index 5fbeb7242b..840dfe2bfd 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -19,6 +19,7 @@ omit = */dmrgscf/*
     */pbc/mpicc/*
     */pbc/mpitools/*
     */gen_*_param.py
+    *slow*
 disable_warnings = include-ignored
 
 [report]
diff --git a/pyscf/df/test/test_df_grad.py b/pyscf/df/test/test_df_grad.py
index 6630def483..affdbfc14b 100644
--- a/pyscf/df/test/test_df_grad.py
+++ b/pyscf/df/test/test_df_grad.py
@@ -47,6 +47,26 @@ def test_rhf_grad(self):
         g1 = scf.RHF(mol).density_fit().run().nuc_grad_method().kernel()
         self.assertAlmostEqual(abs(gref - g1).max(), 0, 5)
 
+    def test_rks_lda_grad(self):
+        gref = mol.RKS(xc='lda,').run().nuc_grad_method().kernel()
+        g1 = mol.RKS(xc='lda,').density_fit().run().nuc_grad_method().kernel()
+        self.assertAlmostEqual(abs(gref - g1).max(), 0, 4)
+
+    def test_rks_grad(self):
+        gref = mol.RKS(xc='b3lyp').run().nuc_grad_method().kernel()
+        g1 = mol.RKS(xc='b3lyp').density_fit().run().nuc_grad_method().kernel()
+        self.assertAlmostEqual(abs(gref - g1).max(), 0, 4)
+
+    def test_uhf_grad(self):
+        gref = mol.UHF.run().nuc_grad_method().kernel()
+        g1 = mol.UHF.density_fit().run().nuc_grad_method().kernel()
+        self.assertAlmostEqual(abs(gref - g1).max(), 0, 5)
+
+    def test_uks_lda_grad(self):
+        gref = mol.UKS.run(xc='lda,').nuc_grad_method().kernel()
+        g1 = mol.UKS.density_fit().run(xc='lda,').nuc_grad_method().kernel()
+        self.assertAlmostEqual(abs(gref - g1).max(), 0, 4)
+
     def test_uks_grad(self):
         gref = mol.UKS.run(xc='b3lyp').nuc_grad_method().kernel()
         g1 = mol.UKS.density_fit().run(xc='b3lyp').nuc_grad_method().kernel()
diff --git a/pyscf/df/test/test_df_hessian.py b/pyscf/df/test/test_df_hessian.py
index fb58b35365..835d37868c 100644
--- a/pyscf/df/test/test_df_hessian.py
+++ b/pyscf/df/test/test_df_hessian.py
@@ -44,16 +44,25 @@ def tearDownModule():
 
 class KnownValues(unittest.TestCase):
     def test_rhf_hess(self):
-        gref = scf.RHF(mol).run().Hessian().kernel()
-        g1 = scf.RHF(mol).density_fit().run().Hessian().kernel()
-        self.assertAlmostEqual(abs(gref - g1).max(), 0, 3)
+        href = scf.RHF(mol).run().Hessian().kernel()
+        h1 = scf.RHF(mol).density_fit().run().Hessian().kernel()
+        self.assertAlmostEqual(abs(href - h1).max(), 0, 3)
+
+    def test_rks_hess(self):
+        href = mol.RKS.run(xc='b3lyp').Hessian().kernel()
+        h1 = mol.RKS.density_fit().run(xc='b3lyp').Hessian().kernel()
+        self.assertAlmostEqual(abs(href - h1).max(), 0, 3)
+
+    def test_uhf_hess(self):
+        href = scf.UHF(mol).run().Hessian().kernel()
+        h1 = scf.UHF(mol).density_fit().run().Hessian().kernel()
+        self.assertAlmostEqual(abs(href - h1).max(), 0, 3)
 
     def test_uks_hess(self):
-        gref = mol.UKS.run(xc='b3lyp').Hessian().kernel()
-        g1 = mol.UKS.density_fit().run(xc='b3lyp').Hessian().kernel()
-        self.assertAlmostEqual(abs(gref - g1).max(), 0, 3)
-#
+        href = mol.UKS.run(xc='b3lyp').Hessian().kernel()
+        h1 = mol.UKS.density_fit().run(xc='b3lyp').Hessian().kernel()
+        self.assertAlmostEqual(abs(href - h1).max(), 0, 3)
+
 if __name__ == "__main__":
     print("Full Tests for df.hessian")
     unittest.main()
-
diff --git a/pyscf/dft/numint2c.py b/pyscf/dft/numint2c.py
index 88d79d017f..4f31676e31 100644
--- a/pyscf/dft/numint2c.py
+++ b/pyscf/dft/numint2c.py
@@ -535,7 +535,7 @@ class NumInt2C(numint._NumIntMixin):
     collinear_thrd = getattr(__config__, 'dft_numint_RnumInt_collinear_thrd', 0.99)
     collinear_samples = getattr(__config__, 'dft_numint_RnumInt_collinear_samples', 200)
 
-    eval_rho = eval_rho
+    eval_rho = staticmethod(eval_rho)
 
     def eval_rho2(self, mol, ao, mo_coeff, mo_occ, non0tab=None, xctype='LDA',
                   with_lapl=True, verbose=None):