FreeGs thermodynamic database project

• FreeGs concept
• FreeGs project, pmd*CRC, and geochemical community
• FreeGs data
• FreeGs implementation stages
• FreeGs vision database
• FreeGs team
• Project partners
• Acknowledgements
• References
• Related links

FreeGs concept

The FreeGs is a web-enabled thermodynamic database of geologically related substances. More about the FreeGs concept can be found in the attached abstract.

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FreeGs project, pmd*CRC, and geochemical community

FreeGs has been developed for the Predictive Mineral Discovery Cooperative Research Centre (pmd*CRC).

FreeGs assists in meeting one of the long-term objectives for the pmd*CRC: to create a computational environment to simulate the 4D evolution of mineral systems. An integral part of such simulation is modelling of geochemical processes over a wide range of temperatures and pressures.

Although primarily serving the pmd*CRC, we believe that FreeGs can benefit the wider geochemical community. Most of FreeGs thermodynamic data can be interrogated by the general public. In turn, we expect that the pmd*CRC will benefit from feedback and contributions by the external geochemical community.

The ultimate vision of FreeGs is as an online collaborative tool for exchange of thermodynamic data between interested geochemists.

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FreeGs data

The initial FreeGs concept was inspired by the desktop UNITHERM database system for the HCh package for geochemical modelling. UNITHERM offers considerable flexibility in the choice of the data formats and integrated algorithms for calculation of thermodynamic properties (Shvarov, 1999; Shvarov & Bastrakov, 1999).

FreeGs contains mineral, gas, and aqueous species parameters that permit calculation of thermodynamic properties over a wide range of geological temperatures and pressures (0–1000°C, 1–5000 bar). The initial set of thermodynamic models and calculation algorithms implemented in FreeGs were selectively extracted from UNITHERM, but we plan to expand this set beyond the current UNITHERM capabilities.

Though FreeGs aims to provide a single authoritative source of thermodynamic data for the pmd*CRC community, it follows the main principle of "multiple choices to multiple users". There are choices of

• the depth of the database interrogation ("casual" or "novice" user vs an "expert")
• the data versions ("recommended" values for the species of interest vs all the available data)
• the available extrapolation models (equations of state)
• formats of the output data (yet to be implemented)

Note that FreeGs is NOT a self-consistent database of thermodynamic properties, nor is internal consistency the goal of the project, though we will strive for a “reasonable” consistency wherever possible. The values that we recommended for the pmd*CRC community are “reasonable” from a modeller’s point of view (i.e., they reproduce the natural or experimental equilibria to the satisfaction of the maintenance team). If you are an external user, we leave the choice of the selected datasets and responsibility for this choice entirely to you.

The overall maintenance, access, and development concept has similarities with the Common Thermodynamic Database Project (CTDP) at the Paris School of Mines, though the latter renders a compilation of selected thermodynamic properties of chemical reactions with all exploitable data available up to 300°C. Similar to CDTP, the constants and values in FreeGs are not forcibly certified, and a confidence-level is attributed instead.

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FreeGs implementation stages

FreeGs is being implemented in the following stages:

• Implementation of the database and the web-based database maintenance system – Completed February 2004
• Database population and maintenance – Ongoing, with the goal to include all major thermodynamic datasets for geochemistry by June 2006
• Implementation of algorithms to calculate selected thermodynamic properties of database species (eg, apparent free energies of formation and log K values of chemical reactions) at high temperatures and pressures – Completed August 2004 (release of Beta version)
• Implementation of a web-feature service (WFS) that will enable users to output the “primary” and recalculated data (eg, Δg(T,P) or log Kr(T,P)) to clients computers and applications using XML – June 2006

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Vision for the FreeGs Database

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FreeGs team

 The current FreeGs development team is as follows:

• Concept – E. Bastrakov¹, Yu. Shvarov², L. Wyborn¹
• Programming – S. Girvan¹, P. Scheffer¹, Yu. Shvarov, D. Percival¹
• Database content maintenance team – E. Bastrakov, J. Cleverley³, D. C. "Bear" McPhail⁴
• Database custodian at Geoscience Australia – E. Bastrakov

¹ Geoscience Australia & pmd*CRC; ² Moscow State University & pmd*CRC; ³ James Cook University & pmd*CRC; ⁴ Australian National University & CRC LEME

FreeGs is an “open” project with the intent of bringing together the researchers involved in modelling of geochemical processes over a wide range of temperatures and pressures. If you are interested in using this system, we encourage you to send us constructive suggestions, bug reports, and data and computational algorithms that you might want to share.

In addition, you can join the database maintenance team with direct access to data entry and editing forms. Please contact us for more details.

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Project partners

Geoscience Australia is a partner in the pmd*CRC. Other pmd*CRC partners directly involved in the FreeGs development and maintenance are:

• James Cook University

Beyond pmd*CRC, the current FreeGs partners are:

• LEME (The Cooperative Research Centre for Landscape Environments and Mineral Exploration) at the Australian National University
• Metals and Solutions (HyDAC) group at the South Australian Museum, University of Adelaide, and CSIRO

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Acknowledgements

• Additional algorithms contribution – Nikolay N. Akinfiev¹

¹ Institute of Geology of Ore Deposits, Moscow, Russia

References

• Bastrakov, E., Shvarov, Y., Girvan, S., Cleverley, J., and Wyborn, L., 2004, FreeGs: web-enabled thermodynamic database for modelling of geochemical processes, in McPhie, J., and McGoldrick, P., editors, Dynamic Earth: Past, present and future. Abstracts of the 17th Australian Geological Convention, Hobart, Tasmania, Australia. February 8-13, No 73, p. 52.
• Shvarov, Y. V., 1999, Algorithmization of the numerical equilibrium modelling of dynamic geochemical processes: Geochemistry International, v. 37, 6, p. 571-576.
• Shvarov, Y. V., and Bastrakov, E. N., 1999, HCh: a software package for geochemical equilibrium modelling. User’s Guide: Australian Geological Survey Organisation, Record 1999/25, 61 p.

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Related links

• Virtual centre for geofluids and thermodynamic data
• Fluids inclusion database project
• FreeGs project
• FreeGs thermodynamic calculator
• HCh package for geochemical modelling