Check the concentrations for each component.
Try to change a zero total concentration into a log(free activity)
≈ −999. This means changing a line saying
T,0 to a line saying
LA,−999.
This will work with components that can not have negative concentrations (that is,
it will work for components like Ca2+, but not for
H+ or e−).
Another possibility if a zero total concentration is given:
try to change it to a small non-zero number, like 1E-15.
If several total concentrations are the same (for example
[Ca2+]tot = [Mg2+]tot =
[CO32−]tot = 0.001 M),
try to change them slightly (for example, set one component to 0.001, the next
to 0.00101, the third to 0.00102, etc).
Impossible chemical systems:
Some redox cases (for example an excess free electrons without any left
material to be reduced) cannot be handled. Try in that case to limit the concentration
range to reasonable values, see for example the input file EX5.DAT
The programs also fail if the activity for a solid component is given,
but some other conditions are also given which make the solid component not stable.
For example:
In very acid media an oxide or carbonate can not have
activity = 1.
A copper(II) compound is not stable under very reducing conditions
(where Cu metal is stable), do not give its activity = 1.
Iron metal is not stable under an oxygen atmosphere: do not set
both the O2(g) and Fe(c) activities to
fixed values.
Input errors should not occur if the input file has been created
with DATABASE. Common errors
if you modify the input file your-self:
Check that all components that are specified as solid
(SOLIDC in the first input line, see data-file format)
indeed do correspond to solid phases. The programs assume that the last SOLIDC
components are the solid ones.
Look for erroneous equilibrium constants and/or stoichiometric coefficients.
Check stoichiometric coefficients: calculate a diagram with SED by setting the
ionic strength to a non-zero value
(for example: 0.1 M). The program will check for electroneutrality
in all equilibrium reactions and give warning messages for non-balanced reactions.
This only works if correct electrical charges are given in the
names of all chemical species.