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[OLD] SIT database


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From: John P. Kaszuba

Subject: SIT database

GWB has databases available for Pitzer and HMW, but not SIT. Any SIT plans in the future? Any way I could write a database called "SIT" and have GWB recognize it? Or is there a way to edit an existing database? I have GWB version 3.1.2. My interest is based on the large availability of SIT parameters for actinide elements.


From: Craig Bethke

Subject: Re: SIT database

The SIT model is similar to the “Pitzer equations� in the sense that it contains a Debye-Hückel-like term and a summation accounting for pair-wise ion interactions. It has, however, a considerably simpler formalism than the Pitzer model. (For example, there are no virial coefficients for ion triplets.)

The easy route is to consider whether SIT can be implemented by constructing an SIT dataset in the HMW format, by setting various coefficients in the Pitzer equations to zero (or leaving them undefined). The “green book� from Oxford contains the equations used to evaluate the HMW model in the exact form implemented within React, so you should start there. Off the top of my head, the E-theta terms in the HMW model may be hard to reconcile with the SIT equations. If that doesn't work, it may be possible to incorporate SIT in a future release of React. Such a modification would be more likely if you would be willing to assist by preparing a thermo dataset containing the SIT coefficients, and helping us test the code. Also, we'd put a modification like this, which of course would be a considerably commitment of programmer time, at higher priority if there is a reasonable level of interest among the GWB user community.

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