qrunch.chemistry.ground_state_problem.calculators.tools.initial_ansatz.hartree_fock
Module designed to generate an initial state circuit that corresponds to a Hartree-Fock wave function.
The Hartree-Fock wave function is an approximation that assumes that the wave function of the electronic system can be taken as s single Slater determinant, or a single spin-adapted configuration state function (CSF) which is a linear combination of Slater determinants that are eigenfunctions of the :math:S^{2} operator. However, in this implementation we do not implement the CSF.
The resulting quantum circuit will have a number of qubits equal to the number of spin orbitals (twice the number of spatial orbitals).
Classes
Class to generate and store information about a Hartree-Fock state. |
- class HartreeFockAnsatz
Bases:
InitialAnsatzClass to generate and store information about a Hartree-Fock state.
This state is intended to be used as an initial state for quantum chemistry calculations with quantum computers. Generally, this state will correspond to a classical bitstring (1, 1, 0,…,1, 1, 0,…,0) where the total number of qubits is 2 * N_s, where N_s = number_of_spatial_orbitals. Each spatial orbital can be populated by an alpha and a beta electron simultaneously. The qubit sites are indexed according to: alpha sites (0, N_s - 1) and beta sites (N_s, 2 * N_s -1).
- __init__(molecular_electron_configuration: MolecularElectronConfiguration) None
Initialize a HartreeFockAnsatz.
- Parameters:
molecular_electron_configuration (MolecularElectronConfiguration) – Molecular electron configuration to use.
- Raises:
ValueError – If the number of alpha electrons is larger than the number of spatial orbitals.
ValueError – If the number of beta electrons is larger than the number of spatial orbitals.
- Return type:
None