Molecular-Level Evaluation of the Thermodynamic Properties of Charged Solutions from Submolar to Molar Ion Concentrations

Sahin Buyukdagli

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arXiv · 2610.15985

Molecular-Level Evaluation of the Thermodynamic Properties of Charged Solutions from Submolar to Molar Ion Concentrations

Sahin Buyukdagli

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Abstract

The accurate estimation of the ionic activity coefficients is paramount for the characterization of the electrochemical reactions driving energy storage processes as well as the biological mechanisms involving ATP hydrolysis. The numerical evaluation of the ionic activity coefficients by computational methods is rendered difficult by the infinite dilution limit involved in the integral identity between the Helmholtz free energy and the equation of state of the electrolyte. By combining a recently introduced self-consistent Debye-Huckel formalism and its analytically tractable low density limit, we develop a computationally efficient approach enabling the accurate calculation of the free energy and the related thermodynamic functions of aqueous electrolytes over a broad range of ionic concentration and electrostatic coupling strength. Via comparison with numerical simulations and experimental data, it is shown that our approach can predict the salt dependence of the Helmholtz free energy, the entropy, and the ionic activity coefficients from the electrostatically driven submolar ion concentrations to the hard-core dominated molar density regime.

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Sahin Buyukdagli. 2026-10-11. Molecular-Level Evaluation of the Thermodynamic Properties of Charged Solutions from Submolar to Molar Ion Concentrations. https://arxiv.org/abs/2610.15985

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