Generate orbital optimized cost functions based on electronic structure Hamiltonians in an active space, based on automatic differentation. Powered by PennyLane using either a Pytorch or Jax backend. Molecular structure calculations are performed with PySCF. Supports gradients and hessians of hybrid cost functions based on orbital rotations and parameterized quantum circuits. We use a parameterization of orbitals by rotating the orthogonal atomic orbitals (OAOs). This code was developed as a tool to enable the calculation of Berry phases in molecular systems, see arXiv:2304.06070.

1. create an anaconda or pip environment.
2. install PyTorch following the instructions in PyTorch's Get Started. (GPU support is not needed for small active spaces)
3. Clone the repository git clone [email protected]:EmielKoridon/auto_oo.git and move into the cloned directory cd auto_oo
4. Install auto_oo and its dependencies with pip install .

Auto_oo requires the following dependencies:

• pytorch this should be installed manually
• numpy
• pennylane (version >= 0.31.1, where the orbital-rotation bug is fixed. See here.
• scipy
• openfermion
• pyscf
• jax

Furthermore in the tutorials, we use cirq to visualize states using Dirac notation.

For an extensive tutorial of the code, see the examples section. For the moment, we provide two jupyer notebooks

1. examples/Tutorial_auto_oo.ipynb - in this introduction to the usage of the code, we implement a orbital-optimized PQC ansatz and optimize it using automatic differentation
2. examples/Tutorial_Berry_phase.ipynb - in this tutorial we show how to use the orbital-optimized PQC ansatz to detect a conical intersection by calculating the Berry phase with the algorithm described in arXiv:2304.06070.

auto_oo
├── README.md
├── pyproject.toml
│
├── examples
│   ├── Tutorial_auto_oo.ipynb
│   └── Tutorial_Berry_phase.ipynb
│
├── src
│   └── auto_oo
│       ├── ansatze
│       │   ├── __init__.py
│       │   ├── kUpCCD.py
│       │   └── uccd.py
│       ├── __init__.py
│       ├── moldata_pyscf.py
│       ├── noisy_oo_pqc.py
│       ├── oo_energy.py
│       ├── oo_pqc.py
│       ├── pqc.py
│       └── utils
│           ├── active_space.py
│           ├── __init__.py
│           ├── miscellaneous.py
│           └── newton_raphson.py
└── test
    └── ...