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problem setting pressure in v5.0.4


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I am a new user working with an older version of GWB, release 5.0.4. I'm trying to change the pressure at which my calculations are carried out. Both the manual and the help files say that I should be able to write into react: "pressure 70 bar" or "P 70 bar." But I am receiving an error in the first case of "unknown command: pressure" and in the second case of "Error: Entry "P" matches commands "pause" "pe" "pH" "phrqpitz" "pickup" "pitzer" "plot" "pluses" "polymorphs" "porosity" "precip" "print" "pwd.""


What am I missing here? Any help is appreciated.


Many thanks, Susan

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Hi Susan,


The "pressure" command only applies to the Act2 and Tact programs. It will affect the position of the water stability limits and the fugacity of gases.


You can't set pressure by entering a value directly in React or the other programs. The stability of minerals and aqueous species is commonly not greatly affected by pressure under near-surface conditions. Gases, on the other hand, are different. You can set their fugacities (like partial pressure) directly by swapping the gas into the basis (ex. swap O2(g) for O2(aq) and set fugacity to 0.2, the partial pressure in the atmosphere).


This is more work, but you might attempt to create your own thermodynamic dataset with data corrected for pressure.


Hope this helps,


Brian Farrell

Aqueous Solutions LLC

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