qat.fermion.chemistry.ucc.get_cluster_ops
- qat.fermion.chemistry.ucc.get_cluster_ops(n_electrons: int, nqbits: Optional[int] = None, noons: Optional[List[float]] = None) List[FermionHamiltonian]
Compute the cluster operators.
- Parameters
n_electrons (int) – The number of active electrons of the system.
nqbits (Optional[int]) – The number of qubits.
noons (Optional[List[float]]) – The natural-orbital occupation numbers \(n_i\), sorted in descending order (from high occupations to low occupations) (doubled due to spin degeneracy).
- Returns
The list of cluster operators \(\{i T_{a}^{i}, a \in \mathcal{I}', i \in \mathcal{O}' \} \cup \{iT_{ab}^{ij}, a>b, i>j, a,b \in \mathcal{I}', i,j \in \mathcal{O}'\}\), with \(\mathcal{I}\) (resp. \(\mathcal{O}\)) the inoccupied (resp. occupied) orbitals.
- Return type
List[FermionHamiltonian]
Note
This function accepts as input the number of qubits or the noons. One of them is needed for the computation of the cluster operators.
n_electronsandn_qbitsmust be even.