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Unexpected crash in Act2


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Dear all,


I have created an activity diagram for Fe-S-O minerals using Act2, and it was based on the default database file thermo.dat. Now I would like to update the diagram by loading a customized thermodynamic database file. It loads the file successfully, but when trying to plot the diagram, the following error is displayed:

Error: Cant swap H2S(aq) for SO4--

Then it offers to press OK or Quit, and tyring both commonly results in program crash


When I use the same thermodynamic data file for plotting a gold solubility diagram, it works no problem.


A suspicion I have is that it might not like a non-stoichiometric pyrrhotite phase (Fe0.875S) that I have in my new thermodynamic database file, this more realistic pyrrhotite (closer to natural phases) I would like to use instead of the troilite that is in the default database. Note that originally the database file had species names as e.g. Fe+2 etc., but I manually edited them back to Fe++ etc. The same I did for dissolved gases that were originally formatted as H2S,aq, but I edited them back into H2S(aq) etc. This caused me some errors in the first place, but after editing the thermo file as outlined above, these errors disappeared.


I attach both the Act2 script and the new database file that I created for testing. Any suggestion concerning this error and possible fixes would be appreciated.


Best regards,





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Hi Thomas:


The problem is exactly as the error message states- in your custom database, you have H2S as a basis species, and SO4-- as a secondary species. So swapping H2S in for SO4 is no longer appropriate. You should be able to add H2S in directly as a basis species, assuming the database is formatted correctly.


Hope that helps,


Tom Meuzelaar

RockWare, Inc.

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