Two versions of ChemShell are available depending on which scripting language is used to control the code, Python or Tcl. We recommend the open source, Python-based version of ChemShell to all new users. The original Tcl-based version is no longer under active development but is still available on request.
The Python-based version of ChemShell is open source software and available free of charge from this website. The latest release (v25.0) is available for download here.
Py-ChemShell 25.0 is suitable for production calculations on all types of systems including materials and biomolecules, and we recommend that new ChemShell users install this version.
Although Py-ChemShell is recommended, we currently continue to maintain the original Tcl-based version of ChemShell and distribute it on request. You will need to obtain a licence for Tcl-Chemshell before the code can be downloaded.
Tcl-ChemShell is licenced under a proprietary STFC licence. We distribute the latest version of the code (v3.7) to academic research groups on receipt of a completed licence agreement and (in the case of non-UK licencees) a licence fee of 500 UK Pounds. Note that the license covers the ChemShell code, not the standalone quantum chemistry or MD codes to which ChemShell provides interfaces, which must be obtained separately.
You can download a copy of the Academic Licence form which should be completed, scanned and emailed to Tom Keal.
To make the licence payment by bank transfer, please see the ChemShell payment instructions.
To pay by credit card please use the ChemShell licence payment site.
In case of any problems making the payment, please contact the STFC Scientific Computing Administration.
UK academic groups should use the Royalty Free licence and do not need to make a payment.
Please note that no changes can be made to the academic or royalty free licence terms and conditions.
For commercial licencing of Tcl-ChemShell, or for any further information please contact Tom Keal.
