Chemqulacs#
Chemqulacs includes quantum chemistry code running on quantum circuit simulators and quantum computers.
Documentation#
Installation#
Chemqulacs requires Python 3.9.8 or later.
pip install git+https://github.com/wmizukami/chemqulacs.git
Usage#
VQECASCI, VQECASSCF and VQECI#
You can perform CASCI and CASSCF with VQE by VQECASCI and VQECASSCF classes, which are implemented using PySCF.
from pyscf import gto, scf
from chemqulacs.util import utils
from chemqulacs.vqe.vqemcscf import VQECASCI, VQECASSCF
# Retrieve geometry of a water molecule from PubChem
geom_water = utils.get_geometry_from_pubchem("water")
# Create PySCF's Mole object
mol = gto.M(atom=geom_water, basis="sto-3g")
# Run SCF calculation (RHF)
mf = scf.RHF(mol)
mf.run()
# Run CASCI with VQE with CAS(2e, 2o)
vqe_casci = VQECASCI(mf, 2, 2)
vqe_casci.kernel()
print(f"VQE-CASCI Energy: {vqe_casci.e_tot}")
# Run CASSCF with VQE with CAS(2e, 2o)
vqe_casscf = VQECASSCF(mf, 2, 2)
vqe_casscf.kernel()
print(f"VQE-CASSCF Energy: {vqe_casscf.e_tot}")
The default options for VQE are as follows:
Fermion-qubit mapping: Jordan-Wigner
Optimizer: Adam
Quantum backend: Qulacs
Ansatz: ParticleConservingU1 with 2 layers
You can change those options via arguments for VQECASCI and VQECASSCF objects, which are then passed to VQECI objects. Please see chemqulacs.vqe.vqeci module for more details.
QSE#
You can run QSE by with VQE as follows.
from pyscf import gto, scf
from chemqulacs.util import utils
from chemqulacs.qse.qse import QSE
from chemqulacs.vqe.vqemcscf import VQECASCI, VQECASSCF
# Retrieve geometry of a water molecule from PubChem
geom_water = utils.get_geometry_from_pubchem("water")
# Create PySCF's Mole object
mol = gto.M(atom=geom_water, basis="sto-3g")
# Run SCF calculation (RHF)
mf = scf.RHF(mol)
mf.run()
# Run CASCI with VQE with CAS(2e, 2o)
vqe_casci = VQECASCI(mf, 2, 2)
vqe_casci.kernel()
print(f"VQE-CASCI Energy: {vqe_casci.e_tot}")
# Run QSE with VQE
qse = QSE(vqe_casci.fcisolver)
qse.gen_excitation_operators("ee", 1)
qse.solve()
Development#
Poetry is used for dependency management.
git clone https://github.com/wmizukami/chemqulacs
cd chemqulacs
poetry install
poetry run pytest
See Makefile for other commands for development.