Thank you for responding Jia! I am attaching a simple input file to generate an EH-pH diagram for Zinc. I have an updated version and am using the default database. I am not seeing any Zn-hydroxide aqueous species that I expect at higher pH. I have no problem with Fe or Mn, for example. I have more complex chemistry to explore planned, but until I understand why there are no Zn-hydroxide species, I feel I cannot rely on this output. The Zn-hydroxide species do not even show up in the swap option as is the case for Fe, Mn, etc. If they are missing in the standard database (and I have seen publications referencing these species in the LLNL database, I would appreciate help in locating a database that does include them. Thanks again for any thoughts on this.
Zn_simple.ac2