diff --git a/pyscf/grad/cmspdft.py b/pyscf/grad/cmspdft.py
index 48a6bb1..1e904ee 100644
--- a/pyscf/grad/cmspdft.py
+++ b/pyscf/grad/cmspdft.py
@@ -359,7 +359,7 @@ def trans_rdm12 (ci1, ci0, *args, **kwargs):
     ci_arr = np.asarray (mc.ci)
 
     mc_grad = mc.nuc_grad_method ()
-    Lis = math.pi * (np.random.rand ((3)) - 0.5)
+    Lis = math.pi * (np.random.rand (3) - 0.5)
     eris = mc.ao2mo (mc.mo_coeff)
 
     dw_test = diab_response (mc_grad, Lis, mo=mc.mo_coeff, ci=mc.ci,
diff --git a/pyscf/grad/mspdft.py b/pyscf/grad/mspdft.py
index 9831a05..e75f0fc 100644
--- a/pyscf/grad/mspdft.py
+++ b/pyscf/grad/mspdft.py
@@ -36,7 +36,7 @@
     from mrh.my_pyscf.fci.csf import CSFFCISolver
 except ModuleNotFoundError:
     # dummy
-    class CSFFCISolver (object):
+    class CSFFCISolver :
         pass
 
 def _unpack_state (state):
@@ -656,9 +656,9 @@ def is_prec (self, xis):
 
     def do_sing_warn (self):
         if self.sing_warned: return
-        self.log.warn (('Model-space frame-rotation Hessian is singular! '
+        self.log.warn ('Model-space frame-rotation Hessian is singular! '
                         'Response equations may not be solvable to arbitrary '
-                        'precision!'))
+                        'precision!')
         self.sing_warned = True
 
 
diff --git a/pyscf/grad/test/test_grad_cmspdft.py b/pyscf/grad/test/test_grad_cmspdft.py
index f66fe71..8c04c64 100644
--- a/pyscf/grad/test/test_grad_cmspdft.py
+++ b/pyscf/grad/test/test_grad_cmspdft.py
@@ -31,7 +31,7 @@
 H  1.102430  0.000000 -0.920125'''
 mol_nosymm = gto.M (atom = h2co_casscf66_631g_xyz, basis = '6-31g', symmetry = False, output='/dev/null', verbose = 0)
 mol_symm = gto.M (atom = h2co_casscf66_631g_xyz, basis = '6-31g', symmetry = True, output='/dev/null', verbose = 0)
-Lis = math.pi * (np.random.rand ((1)) - 0.5)
+Lis = math.pi * (np.random.rand (1) - 0.5)
 def get_mc_ref (mol, ri=False, sam=False):
     mf = scf.RHF (mol)
     if ri: mf = mf.density_fit (auxbasis = df.aug_etb (mol))
diff --git a/pyscf/mcdcft/mcdcft.py b/pyscf/mcdcft/mcdcft.py
index bdd3468..e9ff83d 100644
--- a/pyscf/mcdcft/mcdcft.py
+++ b/pyscf/mcdcft/mcdcft.py
@@ -216,7 +216,7 @@ def __init__(self, scf, ncas, nelecas, my_ot=None, ot_name=None, grids_level=Non
                 # I think this is the same DFCASSCF problem as with the DF-SACASSCF gradients earlier
                 super().__init__()
             keys = set(('e_ot', 'e_mcscf', 'e_states'))
-            self._keys = set ((self.__dict__.keys())).union(keys)
+            self._keys = set (self.__dict__.keys()).union(keys)
             self.grids_level = grids_level
             if my_ot is not None:
                 self._init_ot_grids(my_ot, ot_name, grids_level=grids_level)
diff --git a/pyscf/mcpdft/__init__.py b/pyscf/mcpdft/__init__.py
index c30d6fb..0c6560e 100644
--- a/pyscf/mcpdft/__init__.py
+++ b/pyscf/mcpdft/__init__.py
@@ -56,7 +56,7 @@ def CASCIPDFT (mc_or_mf_or_mol, ot, ncas, nelecas, ncore=None, **kwargs):
 CASSCF=CASSCFPDFT
 CASCI=CASCIPDFT
 
-class MultiStateMCPDFTSolver ():
+class MultiStateMCPDFTSolver :
     pass
     # tag
 
diff --git a/pyscf/mcpdft/_dms.py b/pyscf/mcpdft/_dms.py
index 647f4c6..edde07c 100644
--- a/pyscf/mcpdft/_dms.py
+++ b/pyscf/mcpdft/_dms.py
@@ -26,7 +26,7 @@
     from pyscf import dmrgscf
     DMRGCI = dmrgscf.DMRGCI
 except ImportError:
-    class DMRGCI (object):
+    class DMRGCI :
         pass
 
 def _get_fcisolver (mc, ci, state=0):
diff --git a/pyscf/mcpdft/lpdft.py b/pyscf/mcpdft/lpdft.py
index 7a29b56..4c6362d 100644
--- a/pyscf/mcpdft/lpdft.py
+++ b/pyscf/mcpdft/lpdft.py
@@ -319,7 +319,7 @@ def __init__(self, mc):
         self.si_pdft = None
         self.veff1 = None
         self.veff2 = None
-        self._keys = set((self.__dict__.keys())).union(keys)
+        self._keys = set(self.__dict__.keys()).union(keys)
 
     @property
     def e_states(self):
diff --git a/pyscf/mcpdft/mcpdft.py b/pyscf/mcpdft/mcpdft.py
index a1d242a..e7e43d6 100644
--- a/pyscf/mcpdft/mcpdft.py
+++ b/pyscf/mcpdft/mcpdft.py
@@ -337,7 +337,7 @@ def _get_e_decomp(mc, ot, mo_coeff, ci, e_nuc, h, nelecas):
     return e_1e, e_coul, e_otxc, e_ncwfn
 
 
-class _mcscf_env(object):
+class _mcscf_env:
     '''Prevent MC-SCF step of MC-PDFT from overwriting redefined
     quantities e_states and e_tot '''
 
@@ -365,7 +365,7 @@ def __exit__(self, type, value, traceback):
         self.mc._in_mcscf_env = False
 
 
-class _PDFT():
+class _PDFT:
     # Metaclass parent; unusable on its own
     '''MC-PDFT child class. All total energy quantities (e_tot,
     e_states) are MC-PDFT total energies:
@@ -411,7 +411,7 @@ def __init__(self, scf, ncas, nelecas, my_ot=None, grids_level=None,
                                       'mcscf_mcpdft_conv_tol_ci_fp', 1e-8)
         self.mcscf_kernel = self._mc_class.kernel
         self._in_mcscf_env = False
-        self._keys = set((self.__dict__.keys())).union(keys)
+        self._keys = set(self.__dict__.keys()).union(keys)
         if grids_level is not None:
             grids_attr['level'] = grids_level
         if my_ot is not None:
diff --git a/pyscf/mcpdft/mspdft.py b/pyscf/mcpdft/mspdft.py
index 1879d8a..4496b37 100644
--- a/pyscf/mcpdft/mspdft.py
+++ b/pyscf/mcpdft/mspdft.py
@@ -183,8 +183,8 @@ def si_newton (mc, ci=None, objfn=None, max_cyc=None, conv_tol=None,
     if conv:
         log.note ("{} optimization CONVERGED".format (hdr))
     else:
-        log.note (("{} optimization did not converge after {} "
-                   "cycles".format (hdr, it)))
+        log.note ("{} optimization did not converge after {} "
+                   "cycles".format (hdr, it))
 
     return conv, list (ci)
 
@@ -262,7 +262,7 @@ def __init__(self, mc, diabatizer, diabatize, diabatization):
         self.diabatization = diabatization
         self.si_mcscf = None
         self.si_pdft = None
-        self._keys = set ((self.__dict__.keys ())).union (keys)
+        self._keys = set (self.__dict__.keys ()).union (keys)
 
     @property
     def e_states (self):
diff --git a/pyscf/mcpdft/otfnal.py b/pyscf/mcpdft/otfnal.py
index 134a980..a988cc3 100644
--- a/pyscf/mcpdft/otfnal.py
+++ b/pyscf/mcpdft/otfnal.py
@@ -739,11 +739,11 @@ def get_transfnal (mol, otxc):
     xc_base = OT_HYB_ALIAS.get (xc_base.upper (), xc_base)
     if ',' not in xc_base and _libxc.is_hybrid_or_rsh (xc_base):
         raise NotImplementedError (
-            ('Aliased or built-in translated hybrid or range-separated '
+            'Aliased or built-in translated hybrid or range-separated '
              'functionals\nother than those listed in otfnal.OT_HYB_ALIAS. '
              'Build a compound functional\nstring with a comma separating the '
              'exchange and correlation parts, or use\notfnal.make_hybrid_fnal '
-             'instead.')
+             'instead.'
         )
     ks = dft.RKS (mol)
     ks.xc = xc_base
diff --git a/pyscf/mcpdft/pdft_eff.py b/pyscf/mcpdft/pdft_eff.py
index a4dd409..2273dfe 100644
--- a/pyscf/mcpdft/pdft_eff.py
+++ b/pyscf/mcpdft/pdft_eff.py
@@ -28,7 +28,7 @@
 
 
 # TODO: outcore implementation; can I use properties instead of copying?
-class _ERIS(object):
+class _ERIS:
     '''Stores two-body PDFT on-top effective integral arrays in a form
     compatible with existing MC-SCF kernel and derivative functions.
     Unlike actual eris, PDFT 2-electron effective integrals have 24-fold
diff --git a/pyscf/mcpdft/tfnal_derivs.py b/pyscf/mcpdft/tfnal_derivs.py
index d9a4a2c..66f7fae 100644
--- a/pyscf/mcpdft/tfnal_derivs.py
+++ b/pyscf/mcpdft/tfnal_derivs.py
@@ -274,8 +274,8 @@ def contract_fot(otfnal, fot, rho0, Pi0, rho1, Pi1, unpack=True,
         vrho1, vPi1 = _unpack_sigma_vector(v1, rho0p, Pi0p)
         if ggrad:
             if vot_packed is None:
-                raise RuntimeError(("Cannot evaluate fot.x in terms of "
-                                    "unpacked density gradients without vot_packed"))
+                raise RuntimeError("Cannot evaluate fot.x in terms of "
+                                    "unpacked density gradients without vot_packed")
             vrho2, vPi2 = _unpack_sigma_vector(vot_packed, rho1p, Pi1p)
             if vrho1.shape[0] > 1: vrho1[1:4, :] += vrho2[1:4, :]
             if vPi1.shape[0] > 1:  vPi1[1:4, :] += vPi2[1:4, :]
diff --git a/pyscf/mcpdft/xmspdft.py b/pyscf/mcpdft/xmspdft.py
index dbf5200..4145a24 100644
--- a/pyscf/mcpdft/xmspdft.py
+++ b/pyscf/mcpdft/xmspdft.py
@@ -139,7 +139,7 @@ def safock_energy(mc, **kwargs):
     '''
     dsa_fock = np.zeros(
         int(mc.fcisolver.nroots * (mc.fcisolver.nroots - 1) / 2))
-    # TODO fix, this redundacy...no need to compute fock matrix twice..
+    # TODO fix, this redundancy...no need to compute fock matrix twice..
     e_states, _ = diagonalize_safock(mc)
 
     return np.dot(e_states, mc.weights), dsa_fock, None
diff --git a/pyscf/prop/dip_moment/test/test_mcpdft_pdm.py b/pyscf/prop/dip_moment/test/test_mcpdft_pdm.py
index 1420cb2..b57888a 100644
--- a/pyscf/prop/dip_moment/test/test_mcpdft_pdm.py
+++ b/pyscf/prop/dip_moment/test/test_mcpdft_pdm.py
@@ -46,7 +46,7 @@ def get_mc_ref (mol, ri=False, sa2=False):
 #        ref = ref.reshape (2,2,4,3)[int(ri)]
 #    else:
 #        ref = np.load (os.path.join (topdir, 'h2co_tpbe66_631g_grad_num.npy'))[int(ri)]
- #this refernce is obtained by mcpdft numerical differentiation in pyscf 
+ #this reference is obtained by mcpdft numerical differentiation in pyscf 
  #using central differences with a second order accuracy and step size of 1e-4 
     ref = np.load (os.path.join (topdir, 'h2co_tpbe66_631g_edipole_num.npy'))[int(ri)]
     return mc.run (), ref