Upgrade to Qiskit Nature 0.6.0 (backport #24)

.pylintdict

@@ -1,3 +1,4 @@
+ansatz
 args
 autosummary
 bool
@@ -18,6 +19,8 @@ kwargs
 makefile
 mcscf
 mol
+nalpha
+nbeta
 ndarray
 nelec
 norb

README.md

@@ -35,27 +35,44 @@ Below we show a simple example of how to do this.
 ```python
 from pyscf import gto, scf, mcscf
 
+import numpy as np
+
+from qiskit.algorithms.minimum_eigensolvers import VQE
 from qiskit.algorithms.optimizers import SLSQP
 from qiskit.primitives import Estimator
-from qiskit_nature.second_q.algorithms import GroundStateEigensolver, VQEUCCFactory
-from qiskit_nature.second_q.circuit.library import UCCSD
-from qiskit_nature.second_q.mappers import ParityMapper, QubitConverter
+from qiskit_nature.second_q.algorithms import GroundStateEigensolver
+from qiskit_nature.second_q.circuit.library import HartreeFock, UCCSD
+from qiskit_nature.second_q.mappers import ParityMapper
 
 from qiskit_nature_pyscf import QiskitSolver
 
 mol = gto.M(atom="Li 0 0 0; H 0 0 1.6", basis="sto-3g")
 
 h_f = scf.RHF(mol).run()
 
-norb, nelec = 2, 2
+norb = 2
+nalpha, nbeta = 1, 1
+nelec = nalpha + nbeta
 
 cas = mcscf.CASCI(h_f, norb, nelec)
 
-converter = QubitConverter(ParityMapper(), two_qubit_reduction=True)
+mapper = ParityMapper(num_particles=(nalpha, nbeta))
+
+ansatz = UCCSD(
+    norb,
+    (nalpha, nbeta),
+    mapper,
+    initial_state=HartreeFock(
+        norb,
+        (nalpha, nbeta),
+        mapper,
+    ),
+)
 
-vqe = VQEUCCFactory(Estimator(), UCCSD(), SLSQP())
+vqe = VQE(Estimator(), ansatz, SLSQP())
+vqe.initial_point = np.zeros(ansatz.num_parameters)
 
-algorithm = GroundStateEigensolver(converter, vqe)
+algorithm = GroundStateEigensolver(mapper, vqe)
 
 cas.fcisolver = QiskitSolver(algorithm)
 
@@ -66,3 +83,12 @@ More detailed documentation can be found at
 [Documentation](https://qiskit-community.github.io/qiskit-nature-pyscf/). For more detailed 
 explanations we recommend to check out the documentation of
 [PySCF](https://pyscf.org/) and [Qiskit Nature](https://qiskit.org/documentation/nature/).
+
+
+## Citation
+
+If you use this plugin, please cite the following references:
+
+- PySCF, as per [these instructions](https://github.com/pyscf/pyscf#citing-pyscf).
+- Qiskit, as per the provided [BibTeX file](https://github.com/Qiskit/qiskit/blob/master/Qiskit.bib).
+- Qiskit Nature, as per https://doi.org/10.5281/zenodo.7828767

docs/conf.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2022.
+# (C) Copyright IBM 2022, 2023.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -210,7 +210,7 @@
     "python": ("https://docs.python.org/3", None),
     "numpy": ("https://numpy.org/doc/stable", None),
     "scipy": ("https://docs.scipy.org/doc/scipy", None),
-    "qiskit_nature": ("https://qiskit.org/documentation/nature", None),
+    "qiskit_nature": ("https://qiskit.org/ecosystem/nature", None),
     "qiskit": ("https://qiskit.org/documentation", None),
 }
 

docs/index.rst

@@ -9,6 +9,16 @@ Overview
 To get started we suggest looking at the README on Github `<https://github.com/qiskit-community/qiskit-nature-pyscf/blob/main/README.md>`_.
 
 
+Citation
+========
+
+If you use this plugin, please cite the following references:
+
+- PySCF, as per `these instructions <https://github.com/pyscf/pyscf#citing-pyscf>`_.
+- Qiskit, as per the provided `BibTeX file <https://github.com/Qiskit/qiskit/blob/master/Qiskit.bib>`_.
+- Qiskit Nature, as per https://doi.org/10.5281/zenodo.7828767
+
+
 Next Steps
 =================================
 

qiskit_nature_pyscf/qiskit_solver.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2022.
+# (C) Copyright IBM 2022, 2023.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -49,27 +49,42 @@ class QiskitSolver:
 
         from pyscf import gto, scf, mcscf
 
+        from qiskit.algorithms.minimum_eigensolvers import VQE
         from qiskit.algorithms.optimizers import SLSQP
         from qiskit.primitives import Estimator
-        from qiskit_nature.second_q.algorithms import GroundStateEigensolver, VQEUCCFactory
-        from qiskit_nature.second_q.circuit.library import UCCSD
-        from qiskit_nature.second_q.mappers import ParityMapper, QubitConverter
+        from qiskit_nature.second_q.algorithms import GroundStateEigensolver
+        from qiskit_nature.second_q.circuit.library import HartreeFock, UCCSD
+        from qiskit_nature.second_q.mappers import ParityMapper
 
         from qiskit_nature_pyscf import QiskitSolver
 
         mol = gto.M(atom="Li 0 0 0; H 0 0 1.51", basis="631g*")
 
         h_f = scf.RHF(mol).run()
 
-        norb, nelec = 2, 2
+        norb = 2
+        nalpha, nbeta = 1, 1
+        nelec = nalpha + nbeta
 
         cas = mcscf.CASCI(h_f, norb, nelec)
 
-        converter = QubitConverter(ParityMapper(), two_qubit_reduction=True)
+        mapper = ParityMapper(num_particles=(nalpha, nbeta))
+
+        ansatz = UCCSD(
+            norb,
+            (nalpha, nbeta),
+            mapper,
+            initial_state=HartreeFock(
+                norb,
+                (nalpha, nbeta),
+                mapper,
+            ),
+        )
 
-        vqe = VQEUCCFactory(Estimator(), UCCSD(), SLSQP())
+        vqe = VQE(Estimator(), ansatz, SLSQP())
+        vqe.initial_point = np.zeros(ansatz.num_parameters)
 
-        algorithm = GroundStateEigensolver(converter, vqe)
+        algorithm = GroundStateEigensolver(mapper, vqe)
 
         cas.fcisolver = QiskitSolver(algorithm)
 

releasenotes/notes/compatibility-with-qiskit-nature-0.6-7f1189fe41833678.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Ensures compatibility of this plugin with Qiskit Nature 0.6.
+    The examples are updated in order to avoid triggering deprecation warnings.
+    Using Qiskit Nature 0.5 is still supported.

requirements.txt

@@ -1,3 +1,3 @@
-qiskit-nature>=0.5.*
-pyscf>=2.0.*
-setuptools>=40.1.0,<=65.5.1
+qiskit-nature>=0.6
+pyscf>=2.0
+setuptools>=40.1.0

test/test_qiskit_solver.py

@@ -1,6 +1,6 @@
 # This code is part of Qiskit.
 #
-# (C) Copyright IBM 2022.
+# (C) Copyright IBM 2022, 2023.
 #
 # This code is licensed under the Apache License, Version 2.0. You may
 # obtain a copy of this license in the LICENSE.txt file in the root directory
@@ -16,8 +16,9 @@
 
 from pyscf import gto, scf, mcscf
 
-from qiskit_nature.second_q.algorithms import GroundStateEigensolver, NumPyMinimumEigensolverFactory
-from qiskit_nature.second_q.mappers import JordanWignerMapper, QubitConverter
+from qiskit.algorithms.minimum_eigensolvers import NumPyMinimumEigensolver
+from qiskit_nature.second_q.algorithms import GroundStateEigensolver
+from qiskit_nature.second_q.mappers import JordanWignerMapper
 from qiskit_nature_pyscf.qiskit_solver import QiskitSolver
 
 
@@ -37,8 +38,8 @@ def test_rhf_casci_h2(self):
         qcas = mcscf.CASCI(h_f, norb, nelec)
 
         ground_state_solver = GroundStateEigensolver(
-            QubitConverter(JordanWignerMapper()),
-            NumPyMinimumEigensolverFactory(),
+            JordanWignerMapper(),
+            NumPyMinimumEigensolver(),
         )
 
         qcas.fcisolver = QiskitSolver(ground_state_solver)
@@ -60,8 +61,8 @@ def test_uhf_ucasci_h2(self):
         qcas = mcscf.UCASCI(h_f, norb, nelec)
 
         ground_state_solver = GroundStateEigensolver(
-            QubitConverter(JordanWignerMapper()),
-            NumPyMinimumEigensolverFactory(),
+            JordanWignerMapper(),
+            NumPyMinimumEigensolver(),
         )
 
         qcas.fcisolver = QiskitSolver(ground_state_solver)
@@ -83,8 +84,8 @@ def test_rhf_casscf_h2(self):
         qcas = mcscf.CASSCF(h_f, norb, nelec)
 
         ground_state_solver = GroundStateEigensolver(
-            QubitConverter(JordanWignerMapper()),
-            NumPyMinimumEigensolverFactory(),
+            JordanWignerMapper(),
+            NumPyMinimumEigensolver(),
         )
 
         qcas.fcisolver = QiskitSolver(ground_state_solver)
@@ -106,8 +107,8 @@ def test_uhf_ucasscf_h2(self):
         qcas = mcscf.UCASSCF(h_f, norb, nelec)
 
         ground_state_solver = GroundStateEigensolver(
-            QubitConverter(JordanWignerMapper()),
-            NumPyMinimumEigensolverFactory(),
+            JordanWignerMapper(),
+            NumPyMinimumEigensolver(),
         )
 
         qcas.fcisolver = QiskitSolver(ground_state_solver)