We are delighted to announce the release of Py-ChemShell 2023 (v23.0), the latest release of the Python-based version of ChemShell.

Highlights of the 2023 release include a general purpose multi-layer subtractive embedding scheme, integration with the Basis Set Exchange library, support for residue patching when importing CHARMM forcefields via DL_FIELD, and new interfaces to TURBOMOLE, CASTEP and PySCF.

We consider Py-ChemShell 2023 to be suitable for production calculations on both materials and biomolecular systems, and we recommend that new ChemShell users should use the Python-based version.

We would also like to encourage experienced Tcl-ChemShell users, especially those who use TURBOMOLE as their preferred QM package, to try the biomolecular modelling functionality in Py-ChemShell and send us their feedback, which we will aim to address for the next release in 2024.

Py-ChemShell can be downloaded free of charge under the open source GNU LGPL v3 licence from this site. If you have any questions about the code, please get in touch via the Discourse forum.