The purpose of the PHAST Chemistry Options dialog box is to specify whether solute transport will be used and, if so, which reactants will be used as well as the diffusivity. The PHAST Chemistry Options dialog box is displayed by selecting Model|PHAST Chemistry Options... The options that are available are
•Use solute transport,
•Use equilibrium phases,
•Use surface assemblages,
•Use exchange,
•Use gas phases,
•Use solid solution, and
•Use kinetics.
To use solute transport in a model, the checkbox labeled Use solute transport must be checked. If it is checked, the other options become enabled. A particular reactant will be used in the model if the checkbox next to it is checked. Note however, that even if a checkbox is unchecked, data sets related to that option still will be present in the Data Sets dialog box. However, the data sets that are not used directly in the model will be categorized as optional. Data sets that are not used directly in the model can still be used in the formulas for other data sets and thus may still have an influence on the model. The user must define the reactants to be used in the chemistry data file and define their initial conditions in the appropriate data set for each type of reaction.
The diffusivity in the model is specified in the edit box labeled Diffusivity.
