# PyFLOSIC: Python-based Fermi-L\"owdin orbital self-interaction correction

## TL;DR

PyFLOSIC is an open-source Python implementation of the Fermi-L"owdin orbital self-interaction correction, enabling flexible and efficient quantum chemistry calculations with various basis sets and functionals.

## Contribution

It introduces a modular, Python-based implementation of FLO-SIC integrated with PySCF, supporting automatic initialization and optimization of Fermi-orbital descriptors.

## Key findings

- Supports various basis sets and functionals within PySCF
- Enables automatic initialization and optimization of descriptors
- Facilitates applications and further development of FLO-SIC

## Abstract

We present PyFLOSIC, an open-source, general-purpose Python implementation of the Fermi-L\"owdin orbital self-interaction correction (FLO-SIC), which is based on the Python simulation of chemistry frame-work (PySCF) electronic structure and quantum chemistry code. Thanks to PySCF, PyFLOSIC can be used with any kind of Gaussian-type basis set, various kinds of radial and angular quadrature grids, and all exchange-correlation functionals within the local density approximation (LDA), generalized-gradient approximation (GGA), and meta-GGA provided in the Libxc and XCFun libraries. A central aspect of FLO-SIC are Fermi-orbital descriptors, which are used to estimate the self-interaction correction. Importantly, they can be initialized automatically within PyFLOSIC and optimized with an interface to the atomic simulation environment, a Python library which provides a variety of powerful gradient-based algorithms for geometry optimization. Although PyFLOSIC has already facilitated applications of FLO-SIC to chemical studies, it offers an excellent starting point for further developments in FLO-SIC approaches, thanks to its use of a high-level programming language and pronounced modularity.