Domino can output the stoichiometry of a balanced discontinuous reaction (option 3 for reaction labels), but not a continuous reaction. One way to estimate stoichiometry is to run theriak at two PT points and take the difference in moles (normalized to your favorite phase). However, this is dependent on the locations of the two points and is probably best applied at points along a known PT path.
Is there a different/better method for extracting a balanced continuous reaction using TD?
Eric
Calculate balanced continuous reaction
 Frank Spear
 Posts: 1
 Joined: 28 Oct 2015, 12:56
Re: Calculate balanced continuous reaction
Eric
I agree. The stoichiometry for a reaction in which the phases change composition with P and T (whether continuous or discontinuous) is a function of the P&T and a given stoichiometry is only valid at the specified P&T. Moreover, the stoichiometry for a continuous reaction will vary depending on the PT path. That is, the stoichiometry will be different if the path is isobaric or isothermal. But it is perfectly OK to get the stoichiometry by calculating the assemblage at two closely spaced points and subtracting. A general solution would be to calculate 3 points  one "base" P&T, one isobaric and one isothermal. Subtracting each from the "base" will provide two vectors from which the stoichiometry can be calculated along any PT path by linear combination. A similar result can be obtained by calculating the Jacobian at the "base" PT point, but Theriak doesn't have that code.
I would also recommend when writing the balanced reaction utilizing additive and exchange components. The additive components will specify how the moles (or volumes if you convert using the molar volume) of phases change and the exchange components will specify how each phase changes composition. If you don't do this then you end up with reactions such as .... biotite1 = biotite2 .... (e.g. the same phase on both sides of the reaction but with different compositions) and this formalism isn't too useful for determining how the modes change.
Frank
I agree. The stoichiometry for a reaction in which the phases change composition with P and T (whether continuous or discontinuous) is a function of the P&T and a given stoichiometry is only valid at the specified P&T. Moreover, the stoichiometry for a continuous reaction will vary depending on the PT path. That is, the stoichiometry will be different if the path is isobaric or isothermal. But it is perfectly OK to get the stoichiometry by calculating the assemblage at two closely spaced points and subtracting. A general solution would be to calculate 3 points  one "base" P&T, one isobaric and one isothermal. Subtracting each from the "base" will provide two vectors from which the stoichiometry can be calculated along any PT path by linear combination. A similar result can be obtained by calculating the Jacobian at the "base" PT point, but Theriak doesn't have that code.
I would also recommend when writing the balanced reaction utilizing additive and exchange components. The additive components will specify how the moles (or volumes if you convert using the molar volume) of phases change and the exchange components will specify how each phase changes composition. If you don't do this then you end up with reactions such as .... biotite1 = biotite2 .... (e.g. the same phase on both sides of the reaction but with different compositions) and this formalism isn't too useful for determining how the modes change.
Frank
Re: Calculate balanced continuous reaction
Although I never used it for calculating stochiometry, but would calculating a pixelmap be a way of doing this? The pixelmap results contain the moles of each phase at every pixel in your PT (or wathever) space. From this one could calculate the change in moles of phases from pixel to pixel.
Sina
Sina
Re: Calculate balanced continuous reaction
Frank: Thanks for the comprehensive response.
Following Sina's comment, a pixel map could be useful if many determinations need to be made. However, along a PT path, a loop/drive file would probably be faster. And of course for just two points, simply running theriak at each point would be fastest and easiest.
Eric
Following Sina's comment, a pixel map could be useful if many determinations need to be made. However, along a PT path, a loop/drive file would probably be faster. And of course for just two points, simply running theriak at each point would be fastest and easiest.
Eric

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