 ```python
import numpy as np
from pyscf import gto, scf, cc, df

# Define atomic coordinates, basis, pseudopotential, and lattice vectors
atoms = [('C', (0, 0, 0)), ('C', (2.4, 0, 0))]
basis = 'cc-pvdz'
pseudo = 'gth-pvdz'
lattice = np.eye(3) * 5.4

cell = gto.M(
    atom=atoms,
    basis=basis,
    pseudo=pseudo,
    symmetry='c1',
    lattice=lattice,
    unit='Bohr'
)

# Perform KHF and KCCSD calculations with 2x2x2 k-points
kpts = np.array([[0, 0, 0], [0.5, 0.5, 0.5]])
khf_scf = scf.KRHF(cell, kpts=kpts)
khf_scf.kernel()
kccsd_cc = cc.KCCSD(khf_scf)
kccsd_cc.kernel()
print("KHF and KCCSD energies with 2x2x2 k-points:")
print("KHF energy =", khf_scf.e_tot)
print("KCCSD energy =", kccsd_cc.e_tot)

# Perform KHF and KCCSD calculations for a single k-point
kpts = np.array([[0, 0, 0]])
khf_scf = scf.KRHF(cell, kpts=kpts)
khf_scf.kernel()
kccsd_cc = cc.KCCSD(khf_scf)
kccsd_cc.kernel()
print("KHF and KCCSD energies with a single k-point:")
print("KHF energy =", khf_scf.e_tot)
print("KCCSD energy =", kccsd_cc.e_tot)

# Perform a single k-point calculation using the RHF method, run RCCSD, and print the total energy per unit cell at the k-point
rhf_scf = scf.RHF(cell, kpts=kpts)
rhf_scf.kernel()
rccsd_cc = cc.RCCSD(rhf_scf)
rccsd_cc.kernel()
print("RHF and RCCSD energies with a single k-point:")
print("RHF energy =", rhf_scf.e_tot)
print("RCCSD energy =", rccsd_cc.e_tot)

rccsd_energy_from_dm = cc.rccsd.kernel(rhf_scf, rhf_scf.get_fock(), rccsd_cc.t1, rccsd_cc.t2, verbose=0)
print("RCCSD energy based on CCSD density matrices =", rccsd_energy_from_dm)

# Convert the RHF object to a UHF object, run UCCSD, and print the total energy per unit cell at the k-point
uhf_scf = scf.UHF(cell, kpts=kpts)
uhf_scf.kernel()
uccsd_cc = cc.UCCSD(uhf_scf)
uccsd_cc.kernel()
print("UHF and UCCSD energies with a single k-point:")
print("UHF energy =", uhf_scf.e_tot)
print("UCCSD energy =", uccsd_cc.e_tot)

uccsd_energy_from_dm = cc.uccsd.kernel(uhf_scf, uhf_scf.get_fock(), uccsd_cc.t1, uccsd_cc.t2, verbose=0)
print("UCCSD energy based on CCSD density matrices =", uccsd_energy_from_dm)

# Convert the UHF object to a GHF object, run GCCSD, and print the total energy per unit cell at the k-point
ghf_scf = scf.GHF(cell, kpts=kpts)
ghf_scf.kernel()
gccsd_cc = cc.GCCSD(ghf_scf)
gccsd_cc.kernel()
print("GHF and GCCSD energies with a single k-point:")
print("GHF energy =", ghf_scf.e_tot)
print("GCCSD energy =", gccsd_cc.e_tot)

gccsd_energy_from_dm = cc.gccsd.kernel(ghf_scf, ghf_scf.get_fock(), gccsd_cc.t1, gccsd_cc.t2, verbose=0)
print("GCCSD energy based on CCSD density matrices =", gccsd_energy_from_dm)
```