Force Fields for Deep Eutectic Mixtures: Application to Structure and 2D-Infrared Spectroscopy
Abstract
Parametrizing energy functions for ionic systems can be challenging. Here, the total energy function for an eutectic system consisting of water, SCN, K and acetamide is improved vis-a-vis experimentally measured properties. Given the importance of electrostatic interactions, two different types of models are considered: the first (model M0) uses atom-centered multipole whereas the other two (models M1 and M2) are based on fluctuating minimal distributed charges (fMDCM) that respond to geometrical changes of SCN. The Lennard-Jones parameters of the anion are adjusted to best reproduce experimentally known hydration free energies and densities which are matched to within a few percent for the final models irrespective of the electrostatic model. Molecular dynamics simulations of the eutectic mixtures with varying water content (between 0% and 100%) yield radial distribution functions and frequency correlation functions for the CN-stretch vibration. Comparison with experiments indicate that models based on fMDCM are considerably more consistent that those using multipoles. Computed viscosities from models M1 and M2 are within 30% of measured values and their change with increasing water content is consistent with experiments. This is not the case for model M0.
Cite
@article{arxiv.2408.07638,
title = {Force Fields for Deep Eutectic Mixtures: Application to Structure and 2D-Infrared Spectroscopy},
author = {Kai Töpfer and Eric Boittier and Michael Devereux and Andrea Pasti and Peter Hamm and Markus Meuwly},
journal= {arXiv preprint arXiv:2408.07638},
year = {2024}
}