old_contents: """
  This module is an alias for `pyscf.tdscf.rhf_slow`. It works with single k-point HF objects.
  """
  from pyscf.tdscf.rhf_slow import *
new_contents: """
  This and other `_slow` modules implement the time-dependent Hartree-Fock procedure. The primary performance drawback is
  that, unlike other 'fast' routines with an implicit construction of the eigenvalue problem, these modules construct
  TDHF matrices explicitly via an AO-MO transformation, i.e. with a O(N^5) complexity scaling. As a result, regular
  `numpy.linalg.eig` can be used to retrieve TDHF roots in a reliable fashion without any issues related to the Davidson
  procedure. Several variants of TDHF are available:
  
   * `pyscf.tdscf.rhf.slow`: the molecular implementation;
   * (this module) `pyscf.pbc.tdscf.rhf_slow`: PBC (periodic boundary condition) implementation for RHF objects of
     `pyscf.pbc.scf` modules;
   * `pyscf.pbc.tdscf.krhf_slow_supercell`: PBC implementation for KRHF objects of `pyscf.pbc.scf` modules. Works with
     an arbitrary number of k-points but has a overhead due to an effective construction of a supercell.
   * `pyscf.pbc.tdscf.krhf_slow`: PBC implementation for KRHF objects of `pyscf.pbc.scf` modules. Works with an arbitrary
     number of k-points and employs k-point conservation (diagonalizes matrix blocks separately).
  """
  
  # This module is simply an alias of the molecular code
  from pyscf.tdscf.rhf_slow import *
subject: Extend a docstring in PBC-Gamma TDHF