Problem converging on initial composition

[Tom Meuzelaar 0]

[admin notice: the below is from the former GWB users group email distribution list. This message was originally posted 8/28/2006]

Posted by: Aaron Slowey

Hello,

React is not converging on the initial composition of my system

(08-24-06.rea file attached). The problematic aqueous species seems to be

the anion I specify React to charge balance on (either Cl- or nitrate,

with no effect on residual, etc.).

I'm trying to use the Minteq_gwb4 database, to which I've added 1 new

aqueous species (see attached file). I can load this database without any

error prior to opening the .rea script.

Thanks for any suggestions.

Aaron Slowey

Posted by: Craig Bethke

Hi Aaron,

The model doesn't converge because it is not possible for a chemical system containing cinnabar and H2S to be in equilibrium with a reservoir of dioxygen gas.

If you set a very low oxygen fugacity (say, 10^-80 or so) the simulation runs to completion.

Hope this helps,

Craig