```python
from pyscf import gto, scf, mcscf, dmrgscf
from pyscf.tools import molden

# Define the molecule
mol = gto.Mole()
mol.atom = '''
Fe 0 0 0
N  0 0 1.1
N  0 1.1 0
N  0 0 -1.1
N  0 -1.1 0
'''
mol.basis = 'cc-pVDZ'
mol.spin = 4  # Quintet state
mol.build()

# Perform a mean-field calculation
mf = scf.RHF(mol)
mf.kernel()

# Define the active space
ncas = 10  # Number of active orbitals
nelecas = (9, 9)  # Number of electrons in active space
# Fe double d-shell (5 orbitals), 4s shell (1 orbital), ligand N 2pz orbitals (4 orbitals)

# Perform CASSCF calculation to get the orbitals
mc = mcscf.CASSCF(mf, ncas, nelecas)
mc.kernel()

# Save active space orbitals to a molden file
molden.from_mo(mol, 'FePorphyrin_active_orbitals.molden', mc.mo_coeff[:, mc.ncore:mc.ncore+ncas])

# Setup DMRG as the solver for CASSCF
mc.fcisolver = dmrgscf.DMRGSCF(mol, ncas, nelecas)
mc.fcisolver.maxM = 1000  # Maximum bond dimension

# Calculate quintet state energy
E_quintet = mc.kernel()[0]

# Change the spin state to triplet and recalculate
mol.spin = 2  # Triplet state
mf = scf.RHF(mol)
mf.kernel()
mc = mcscf.CASSCF(mf, ncas, nelecas)
mc.fcisolver = dmrgscf.DMRGSCF(mol, ncas, nelecas)
mc.fcisolver.maxM = 1000
E_triplet = mc.kernel()[0]

# Calculate energy gaps
gap = E_triplet - E_quintet

print(f"Quintet Energy: {E_quintet}")
print(f"Triplet Energy: {E_triplet}")
print(f"Energy Gap: {gap}")
```