Sequence of PHREEQC calculations

[MichaelZ20]

Hi, David!
I have not found a place of SOLID_SOLUTION calculations in the sequence of calculations described in the manual. Where is it?

[dlparkhurst]

For non-ideal binary solid solutions, there is a calculation to determine the critical temperature, spinodal gap, miscibility gap, etc. This calculation occurs occurs just after reading END that includes the SOLID_SOLUTION data block. The calculation does not involve interaction with a solution. The results are printed in a section of output labeled "Description of Solid Solution xxx". There is no calculation or output for an ideal solid solution.

The same code is called whenever the temperature changes, although there is no printout. Think of it as an extra temperature-dependent calculation like calculating log Ks for the phases.

There is no other SOLID_SOLUTION-specific calculation. Basically, a solid solution in SOLID_SOLUTION is used in the same way as a phase in EQUILIBRIUM_PHASES. When included, the solid solution reacts to equilibrium with the solution or dissolves entirely.