README

About

These codes perform the Kirkwood-Buff inversion procedure for mixed electrolyte solutions and extract the ion-ion Kirkwood-Buff Integrals (KBIs). PitzerSaltMixtureKBI.f95 calculates the component-based KBIs, using the indistinguishable ion approach. These codes are setup to use Pitzer parameters for the electrolyte activity coefficients and for the electrolyte partial molar volumes. indistingToDisting.f95 calculates ion-ion KBIs, using the component-based KBIs output from PitzerSaltMixtureKBI.f95 as input. The example input files are setup for the system NaCl + KBr (aq).

Usage

These codes require a Fortran compiler.

KB Inversion Code

To compile the code:

gfortran PitzerSaltMixtureKBI.f95 -o PitzerSaltMixtureKBI

Setup the *.dat files for the system you wish to analyze. To run the code:

nohup ./PitzerSaltMixtureKBI >& myPitzerSaltMixtureKBI &

Indistinguishable to Distinguishable Code

Copy the fort.201, fort.202, and fort.500 output of PitzerSaltMixtureKBI.f95 to the directory where the indistingToDisting.f95 code will be ran. Delete the first line (pure solvent composition) from the files fort.201, fort.202, and fort.500 files.

To compile the code:

gfortran indistingToDisting.f95 -o indistingToDisting

To run the code:

nohup ./indistingToDisting >& myindistingToDisting &

Reference

E.A. Ploetz and P.E. Smith, "Quantifying Ion-Ion Association in Mixed Electrolyte Systems Using Bulk Thermodynamic Experimental Data" Journal of Chemical Physics, 2026, Accepted, DOI: 10.1063/5.0336711

Maintainer

@FluctuationSolutionTheory

License

AGPL-v3.0 © 2026 [Elizabeth A. Ploetz and Paul E. Smith]

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program (see LICENSE file).