No attribute 'MolecularData'

PennyLane Help
1

I am trying to follow the tutorial https://pennylane.ai/qml/demos/tutorial_vqe.html .

import numpy as np
symbols = [“H”, “H”]
coordinates = np.array([0.0, 0.0, -0.6614, 0.0, 0.0, 0.6614])

import pennylane as qml

H, qubits = qml.qchem.molecular_hamiltonian(symbols, coordinates) print("Number of qubits = ", qubits)
print("The Hamiltonian is ", H)

But I got this output:
AttributeError: module ‘pennylane_qchem.qchem.openfermion’ has no attribute ‘MolecularData’.

Thanks!

2

Hi @kennethlee897 and welcome to the forum!

This seems like an installation issue. Could you please make sure that you have installed all the requirements listed here by re-installing qchem with pip install pennylane-qchem? If the error still remains, could you please run the following two commands separately and copy the outputs here?

  1. qml.about()

  2. pip show openfermion

Thanks.

3

The error still remains. For 1. it shows:

Name: PennyLane
Version: 0.16.0
Summary: PennyLane is a Python quantum machine learning library by Xanadu Inc.
Home-page: https://github.com/XanaduAI/pennylane
Author: None
Author-email: None
License: Apache License 2.0
Location: /Users/kennethlee897/anaconda3/lib/python3.6/site-packages
Requires: semantic-version, appdirs, toml, scipy, numpy, autoray, networkx, autograd
Required-by: PennyLane-SF, PennyLane-Qchem
Platform info: Darwin-20.4.0-x86_64-i386-64bit
Python version: 3.6.4
Numpy version: 1.19.5
Scipy version: 1.5.4
Installed devices:

  • default.gaussian (PennyLane-0.16.0)
  • default.mixed (PennyLane-0.16.0)
  • default.qubit (PennyLane-0.16.0)
  • default.qubit.autograd (PennyLane-0.16.0)
  • default.qubit.jax (PennyLane-0.16.0)
  • default.qubit.tf (PennyLane-0.16.0)
  • default.tensor (PennyLane-0.16.0)
  • default.tensor.tf (PennyLane-0.16.0)
  • strawberryfields.fock (PennyLane-SF-0.16.0)
  • strawberryfields.gaussian (PennyLane-SF-0.16.0)
  • strawberryfields.gbs (PennyLane-SF-0.16.0)
  • strawberryfields.remote (PennyLane-SF-0.16.0)
  • strawberryfields.tf (PennyLane-SF-0.16.0)
4

For 2., it show:

and 2.

Name: openfermion

Version: 1.0.1

Summary: The electronic structure package for quantum computers.

Home-page: http://www.openfermion.org

Author: The OpenFermion Developers

Author-email: help@openfermion.org

License: Apache 2

Location: /Users/kennethlee897/anaconda3/lib/python3.6/site-packages

Requires: h5py, deprecation, cirq, numpy, sympy, pubchempy, nbformat, scipy, requests, networkx

Required-by: PennyLane-Qchem, openfermionpyscf, openfermionpsi4

5

Hi @kennethlee897 and thanks for the info. Please note that PennyLane requires Python version 3.7 and above while your Python version is 3.6.4. I recommend installing a higher version of python and then reinstalling both PennyLane and PennyLane-Qchem. That should fix the issue but please let me know if you face any problems. Thanks.