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Paul Scherrer Institut PSI GEM Software (GEMS) Home

Paul Scherrer Institut
5232 Villigen PSI, Schweiz/Switzerland
Tel. +41 56 310 21 11
Fax. +41 56 310 21 99

E-Mail: gems2.support@psi.ch

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GEMS Logo GEM-Selektor v.3 (GEMS3):

Interactive Package for Thermodynamic Modelling of Aquatic (Geo)Chemical Systems by Gibbs Energy Minimization

GEMS3 code package offers high chemical plausibility of (partial) equilibrium thermodynamic models

  • Stable and metastable phases are checked using rigorous criteria based on phase stability index

  • Aqueous equilbria may involve many (non)ideal solid or liquid solutions, gas mixture or non-ideal gaseous fluids

  • Multi-site-surface complexation on mineral-water interfaces can be computed, also without site balances

  • Redox state is calculated from the bulk chemical composition of the system via the GEM dual solution

  • Processes of chemical mass transfer can be simulated using principles of local and partial equilibrium

  • Simple cases of reactive transport (water-rock interaction, 1-D columns) can be simulated in GEM2MT module
  • Built-in default chemical thermodynamic database is provided; third-party databases are also available

  • Thermodynamic data is automatically corrected for temperature and pressure of interest

  • GEMS3K - the standalone kernel of GEMS3 can be coupled to mass-transport or parameter-fitting codes

  • Qt5- based Graphical User Interface with plotting of results and a context-sensitive run-time help system

  • Installers available for all major PC platforms (Windows 10; Macos 10.11 to 10.15; Ubuntu linux 18.04 LTS)

The complexity of chemical system setup is limited mainly by the availability of thermodynamic data for species and phases.

Download Docs Examples Status TechInfo

To learn quickly how to work with the user-friendly GEMS3 code:

  •  download it; install as described in TechInfo page; start the program; click on the 'Help' toolbar button; read instructions there.   

If you  experience a problem, please report it in an e-mail to GEMS Development Team.   Frequently asked questions.

GEMS3 software package is always under development. GEMS is distributed "as is" by the Laboratory for Waste Management (LES) of the Paul Scherrer Institute (PSI) with two purposes:

  • to promote the GEM method and software into research community;
  • to gather the users feedback - vital for making the software more functional and reliable.

Permission to use the GEM-Selektor software is hereby granted free of charge for educational and research purposes, subject to acceptance of Terms and Conditions of Use. Starting from version 3.6.0, GEM-Selektor GUI part is available open-source under the GPL v.3 license.

In any publication of your results obtained using the GEM-Selektor code, please, cite this web page address (https://gems.web.psi.ch) and the following papers:

  • Kulik D.A., Wagner T., Dmytrieva S.V., Kosakowski G., Hingerl F.F., Chudnenko K.V., Berner U. (2013): GEM-Selektor geochemical modeling package: revised algorithm and GEMS3K numerical kernel for coupled simulation codes. Computational Geosciences 17, 1-24. doi.

  • Wagner T., Kulik D.A., Hingerl F.F., Dmytrieva S.V. (2012): GEM-Selektor geochemical modeling package: TSolMod library and data interface for multicomponent phase models. Canadian Mineralogist 50, 1173-1195. doi.

Please, keep in mind that the TSolMod library is an integral part of GEMS codes that is used in solving for equilibrium in any system containing at least one solution (multi-component) phase. Even the simplest aquatic equilibrium calculation makes use of Davies or Debye-H�ckel models that are implemented consistently in TSolMod library. If sophisticated models for non-ideal fluids or solid solutions are used, then citing the paper about TSolMod will streamline and shorten your manuscript letting you concentrate on relevant problem setting and results. 


Copyright (c) 2003-2023 GEMS Development Team

Last update: 10.05.2023