Preparing the POP File for Alternate Mode

Information in your POP file that concerns equilibria with ENTERED or DORMANT phases is ignored when you optimize in alternate mode.

To use the alternate mode, ensure that there is enough information about each phase in a given equilibrium. In addition to the temperature and pressure of the system, you should specify the composition of all phases in a given equilibrium. This is done with, SET_CONDITION, EXPERIMENT, or SET_ALTERNATE_CONDITION.

If both compositions of a binary tie-line have been measured, then you could specify this in the POP file in the following way:

CREATE_NEW_EQUILIBRIUM 1 1

CHANGE_STATUS PHASE FCC BCC=FIX 1

SET_CONDITION P=1E5 T=1000

EXPERIMENT X(BCC,B)=.2:.01 X(FCC,B)=.3:.01

This equilibrium could be calculated with alternate mode without any modification. The compositions specified with the experiment command is used as condition when the thermodynamic properties of each phase are calculated.