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

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

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

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:

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 ( and the following papers:

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. 


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Last update: 10.05.2023


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