Quick start

To quickly install and run Qibochem, open a terminal with python >= 3.9 and type:

pip install qibochem

Here is an example of building the UCCD ansatz with the H2 molecule to test your installation:

import numpy as np
from qibo.models import VQE

from qibochem.driver.molecule import Molecule
from qibochem.ansatz.hf_reference import hf_circuit
from qibochem.ansatz.ucc import ucc_circuit

# Define the H2 molecule and obtain its 1-/2- electron integrals with PySCF
h2 = Molecule([('H', (0.0, 0.0, 0.0)), ('H', (0.0, 0.0, 0.7))])
h2.run_pyscf()
# Generate the molecular Hamiltonian
hamiltonian = h2.hamiltonian()

# Build a UCC circuit ansatz for running VQE
circuit = hf_circuit(h2.nso, h2.nelec)
circuit += ucc_circuit(h2.nso, [0, 1, 2, 3])

# Create and run the VQE, starting with random initial parameters
vqe = VQE(circuit, hamiltonian)

initial_parameters = np.random.uniform(0.0, 2*np.pi, 8)
best, params, extra = vqe.minimize(initial_parameters)