Approximate additivity in the solvent-mediated potential of mean force for ultrasoft particle systems
Abstract
Recently an approximate additivity principle has been successfully applied to molecular chemical potentials in ultrasoft particle systems [R. L. Hendrikse, C. Amador and M. R. Wilson, Phys. Chem. Chem. Phys. 27, 1554 (2025)]. We articulate this additivity principle as one of two ansätze and apply these to dimers in the infinite dilution limit. In this limit, we show that the solvent-mediated potential of mean force (PMF) between solutes, extracted from the hypernetted-chain (HNC) closure of the Ornstein-Zernike equations, can be expressed as a convolution between solute-specific generalised excluded volume functions. In the limit of a structureless solvent of point particles and hard core solutes, this recovers the exact Asakura-Oosawa depletion potential as the overlap between excluded volume spheres. The theory extends to the opposite limit of ultrasoft particle solvents and solutes, such as those encountered in dissipative particle dynamics (DPD), where the solvent-mediated PMF can be recovered with considerable accuracy. These results confirm that in coarse-grained molecular DPD simulations the parametrisation of the solute-solvent interactions is sensitive to the intramolecular bond lengths if they are smaller than the range of the solvent-solvent interaction potential, due to the overlap of the soft excluded volume functions.
Versions
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BibTeX
@misc{robinson2026approximate,
title = {{Approximate additivity in the solvent-mediated potential of mean force for ultrasoft particle systems}},
author = {Joshua F. Robinson and Gary Yu and Patrick B. Warren},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.12275},
eprint = {2606.12275},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.12275},
}
RIS
TY - UNPB
TI - Approximate additivity in the solvent-mediated potential of mean force for ultrasoft particle systems
AU - Joshua F. Robinson
AU - Gary Yu
AU - Patrick B. Warren
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2606.12275
UR - https://arxiv.org/abs/2606.12275
AB - Recently an approximate additivity principle has been successfully applied to molecular chemical potentials in ultrasoft particle systems [R. L. Hendrikse, C. Amador and M. R. Wilson, Phys. Chem. Chem. Phys. 27, 1554 (2025)]. We articulate this additivity principle as one of two ansätze and apply these to dimers in the infinite dilution limit. In this limit, we show that the solvent-mediated potential of mean force (PMF) between solutes, extracted from the hypernetted-chain (HNC) closure of the Ornstein-Zernike equations, can be expressed as a convolution between solute-specific generalised excluded volume functions. In the limit of a structureless solvent of point particles and hard core solutes, this recovers the exact Asakura-Oosawa depletion potential as the overlap between excluded volume spheres. The theory extends to the opposite limit of ultrasoft particle solvents and solutes, such as those encountered in dissipative particle dynamics (DPD), where the solvent-mediated PMF can be recovered with considerable accuracy. These results confirm that in coarse-grained molecular DPD simulations the parametrisation of the solute-solvent interactions is sensitive to the intramolecular bond lengths if they are smaller than the range of the solvent-solvent interaction potential, due to the overlap of the soft excluded volume functions.
ER -