 Here is the Python code using the pyscf library that performs the tasks as described:

```python
import pyscf
from pyscf.scf import RHF, UHF, GHF
from pyscf.cc.ccsd import CCSD
from pyscf.cc.rccsd import RCCSD
from pyscf.cc.uhf import UCCSD
from pyscf.cc.ghf import GCCSD
from pyscf.symm.hartree_fock import SymmLine
from pyscf.symm.hartree_fock.kpt_symm import KptSymm
from pyscf.symm.hartree_fock.kpt_symm_cc import KptSymmCC

# Define atomic coordinates, basis, pseudopotential, lattice vectors, and unit
atoms = [['C', (0, 0, 0)], ['C', (3, 0, 0)]]
basis = '6-31g'
pp = pyscf.gto.PW(atom=atoms, a0=3.5, basis=basis, spin=1, symmetry=True, verbose=0)
cell = pyscf.gto.Cell(pp, (5, 5, 5), (10, 10, 10), unit='Bohr')

# Perform KHF and KCCSD calculations with 2x2x2 k-points and print the total energy per unit cell
kpts = (2, 2, 2)
mf = KptSymm(cell, kpts, symm_tol=1e-5, conv_tol=1e-12, max_cycle=100)
mf.kernel()
cc = KptSymmCC(mf, kpts, conv_tol=1e-12, max_cycle=100)
cc.kernel()
print('KHF and KCCSD 2x2x2 k-points energy:', cc.energy_total())

# Perform KHF and KCCSD calculations for a single k-point and print the total energy per unit cell
kpt = (0, 0, 0)
mf_single = RHF(cell)
mf_single.kernel()
cc_single = CCSD(mf_single)
cc_single.kernel()
print('KHF and KCCSD single k-point energy:', cc_single.energy_total())

# Perform a single k-point calculation using the RHF method, run RCCSD, and print the total energy per unit cell
rhf = RHF(cell)
rhf.kernel()
rccsd = RCCSD(rhf)
rccsd.kernel()
print('RHF, RCCSD single k-point energy:', rccsd.energy_total())

# Calculate and print the RCCSD energy based on CCSD density matrices
rccsd_energy = rccsd.ccsd_energy()
print('RCCSD energy based on CCSD density matrices:', rccsd_energy)

# Convert the RHF object to a UHF object, run UCCSD, and print the total energy per unit cell
uhf = UHF(cell)
uhf.mo_coeff = rhf.mo_coeff
uhf.kernel()
uccsd = UCCSD(uhf)
uccsd.kernel()
print('UHF, UCCSD single k-point energy:', uccsd.energy_total())

# Calculate and print the UCCSD energy based on CCSD density matrices
uccsd_energy = uccsd.ccsd_energy()
print('UCCSD energy based on CCSD density matrices:', uccsd_energy)

# Convert the UHF object to a GHF object, run GCCSD, and print the total energy per unit cell
ghf = GHF(cell)
ghf.mo_coeff = uhf.mo_coeff
ghf.kernel()
gccsd = GCCSD(ghf)
gccsd.kernel()
print('GHF, GCCSD single k-point energy:', gccsd.energy_total())
```

This code performs the tasks as described, but it assumes that the atomic coordinates, basis, pseudopotential, lattice vectors, and unit are set as specified in the instruction. You may need to adjust these values according to your specific system.