Hello! Following the Initial state preparation for quantum chemistry tutorial, is there anyway to create the CISD initial state, but for an active-space, like of which we can specify in Pennylane’s `qml.qchem.molecular_hamiltonian `

? I tried to do so, but it’s giving me an error

Here is the self-contained code:

```
import pennylane as qml
from pennylane import qchem
from pennylane import numpy as np
import time
from pyscf import gto, scf, ci
from pennylane.qchem import import_state
from pennylane import numpy as np
def circuit(theta, initial_state):
# prepares reference state
qml.StatePrep(initial_state, wires=range(qubits))
# apply 2 gates for simplicty:
qml.SingleExcitation(params[0], wires=[1, 3])
qml.DoubleExcitation(params[1], wires=[0, 1, 4, 5])
# returns expectation value of the ansatz prepared from this quantum circuit:
return qml.expval(hamiltonian)
def H(x):
return qml.qchem.molecular_hamiltonian(symbols, x, charge=0, active_electrons = active_electrons,
active_orbitals = active_orbitals)[0]
symbols = ["O", "H", "H"]
active_electrons = 2; active_orbitals = 3
qubits = active_orbitals * 2
theta = np.array([0.0] * 2, requires_grad=True)
x = np.array([0.028, 0.054, 0.0, 0.986, 1.610, 0.0, 1.855, 0.002, 0.0], requires_grad=True)
hamiltonian = H(x)
# create the H2O molecule
mol = gto.M(atom=[["O", (0.028, 0.054, 0.0)],
["H", (0.986, 1.610, 0.0)],
["H", (1.855, 0.002, 0.0)]], charge=0)
# Create cisd initial state for the selected active-space
# prepare for active space of 2-electrons, 3-orbitals
mol.nelectron = 2
mol.build()
# perfrom restricted Hartree-Fock and then CISD
myhf = scf.RHF(mol).run()
myci = ci.CISD(myhf).run()
wf_cisd = import_state(myci, tol=1e-1)
print(f"CISD-based state vector: \n{np.round(wf_cisd.real, 4)}")
# Finally, calculate observable
print(circuit(theta, wf_cisd))
```

And here is the error in question:

```
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
Cell In[1], line 49
46 print(f"CISD-based state vector: \n{np.round(wf_cisd.real, 4)}")
48 # Finally, calculate observable
---> 49 print(circuit(theta, wf_cisd))
Cell In[1], line 12, in circuit(theta, initial_state)
10 def circuit(theta, initial_state):
11 # prepares reference state
---> 12 qml.StatePrep(initial_state, wires=range(qubits))
14 # apply 2 gates for simplicty:
15 qml.SingleExcitation(params[0], wires=[1, 3])
File ~/anaconda3/lib/python3.11/site-packages/pennylane/ops/qubit/state_preparation.py:176, in StatePrep.__init__(self, state, wires, id)
174 state = math.reshape(state, (1, state.shape[0]))
175 if state.shape[1] != 2 ** len(self.wires):
--> 176 raise ValueError("State vector must have shape (2**wires,) or (batch_size, 2**wires).")
178 param = math.cast(state, np.complex128)
179 if not math.is_abstract(param):
ValueError: State vector must have shape (2**wires,) or (batch_size, 2**wires).
```

Thanks so much!