These Matlab scripts are used to obtain symbolic expressions for the thermodynamic constributions to the distinguishable ion-ion Kirkwood-Buff integrals (KBIs) as linear combinations of indistinguishable ion KBIs.
For the common ion case, the provided Matlab script CommonAnion.m symbolically inverts the 6×6 matrix formed from the three electroneutrality plus three indistinguishable ion KBI equations
to provide expressions for the six distinguishable ion-ion KBIs in terms of the three indistinguishable ion KBIs. The example code is setup for I = 1.5 M CaCl2 + 0.5 M NaCl (aq) but could easily be setup for other
common anion or common cation systems. For example, to setup the code instead for the common cation case, simply perform the following index changes to the provided common anion code: + will become –,
+' will become –', and – will become +. Likewise, Binary.m symbolically inverts the 10×10 matrix formed from the four electroneutrality plus six indistinguishable ion KBI equations applicable to a binary salt
mixture of I and I' to provide expressions for the ten distinguishable ion-ion KBIs in terms of six indistinguishable ion KBIs. For both Matlab scripts, the number of ions of each type
is used as input, but molarities could be used instead. The other input required is the formal charge on the ions in the system. If the results are desired for any composition, f can be kept as a symbolic variable
instead of being evaluated numerically. For more information, see our article, referenced below.
matlab -nodisplay -nosplash -nodesktop -r "run('CommonAnion.m');exit;" >& myCommonAnion.out
matlab -nodisplay -nosplash -nodesktop -r "run('Binary.m');exit;" >& myBinary.out
E.A. Ploetz, N.D. Smyers, and P.E. Smith, "Ion-Ion Association in Bulk Mixed Electrolytes Using Global and Local Electroneutrality Constraints" Journal of Physical Chemistry B, 2025, 129, 4, 1387–1398. (Editors' Choice)
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