HgCl 2 /ϵ: A New Force Field for Solid and Aqueous Solution A Molecular Dynamics Study

Abstract A new force eld for divalent mercury Hg 2+ was developed through a systematic parametrisation,adjusted to reproduce the crystalline density of mercury(II) chloride (HgCl 2) in its solid state. The model was calibrated by reproducing the experimental density of (HgCl 2) under ambient pressure (1 bar) across a range of temperatures, thereby ensuring an accurate representation of its thermodynamic behaviour in the condensed phase. To evaluate the transferability and robustness of the developed force eld beyond the pure compound, we conducted molecular simulations of binary aqueous systems employing the TIP4P/ϵ water model. This framework enabled an in-depth characterisation of the mixture's structural and dynamical properties across a spectrum of concentrations, including those beneath the solubility threshold. The results yield highly congruent values with minimal deviation, particularly in terms of solution density and ionic dif-fusivities. Furthermore, we provide estimations of the static dielectric constant of the 1 mixture, thereby reinforcing the validity and predictive delity of the parametrised model.