KPM Tools

KPM Tools is an open-source Python package that extends the Kernel Polynomial Method (KPM) functionalities of Kwant, a popular software for quantum transport simulations in tight-binding models. Our package specifically enhances the KPM expansion capabilities within the realm of closed tight-binding systems.

Features

• Advanced KPM expansion of typical spectral functions like Density of States, Green's Functions, Kubo Conductivity, and Chern Markers.
• Extremely efficient time evolution operator expansion
• Additional functionalities like KPM vector factories producing tiles, and velocity and distance operators adapted to periodic boundaries.

Requirements

• Python >=3.11, <3.13
• Kwant >= 1.4.4
• NumPy <2.0 (required by Kwant, see the note below)

Installation

Installing KPM Tools

You can install KPM Tools via pip from PyPI:

$ pip install kpm-tools

Important Note on Kwant Dependency

While KPM Tools requires Kwant to function, direct installation of Kwant via pip can sometimes be problematic due to its specific build requirements. To ensure a smooth setup, we recommend the following installation approach:

1. Try installing with pip (optional):

   You can attempt to install Kwant along with KPM Tools via pip:

   $ pip install kpm-tools[kwant]
   

   If this installation fails, proceed to the next step.

2. Install Kwant using Conda or follow Kwant's installation guide:

   We recommend using Conda to install Kwant, which typically handles its build requirements more reliably:

   $ conda install -c conda-forge kwant
   

   Alternatively, refer to the Kwant installation page for detailed instructions on installing Kwant in different environments.

After installing Kwant, you can then install KPM Tools using pip as shown above.

Note on NumPy 2: Kwant is currently incompatible with NumPy 2.x — the C sources in its published release access a NumPy internal that became opaque in 2.0, so it fails to compile. KPM Tools therefore constrains numpy<2.0 (and scipy<1.14, which would otherwise pull NumPy 2 in). This constraint will be relaxed once Kwant publishes a NumPy 2 compatible release.

Python API

Please see the python api reference for details.

Contributing

Contributions, especially in documentation and the 'concatenator' function/module, are very welcome. For more information, see our Contributor Guide.

License

Distributed under the terms of the BSD 2-Clause license, KPM Tools is free and open source software.

Issues

If you encounter any problems, please file an issue along with a detailed description.

Credits

Many of the ideas implemented in KPM Tools originate from the early work on KPM expansion on the paper

Computation of topological phase diagram of disordered PbSnTe using the kernel polynomial method.

Phys. Rev. Research 2, 013229 (2020) arXiv:1905:02215

Consider citing that work if you use this package on a publication.

Acknowledgments to Kwant

KPM Tools is built upon the robust and efficient foundation provided by Kwant. We extend our gratitude to the Kwant authors and contributors for their work in developing a versatile platform for quantum transport simulations. KPM Tools aims to complement Kwant's capabilities in KPM expansions, adhering to the high standards of quality and performance set by the Kwant project.

See the original KPM implementation in Kwant: https://kwant-project.org/doc/1/tutorial/kpm https://kwant-project.org/doc/1/reference/kwant.kpm

Project Template

This project was generated from @cjolowicz's Hypermodern Python Cookiecutter template.