ABSTRACT Accurately describing the hydration structure and dynamics of remains challenging for ab initio simulations because relativistic effects, electron correlation, and polarisation lead to a delicate balance between ion–water attraction and ligand mobility. Here, we assessed the SCAN meta‐GGA functional with D3BJ dispersion correction within the quantum‐mechanical charge‐field molecular dynamics (QMCF MD) framework for hydration, using a 175 ps trajectory with a quantum region spanning the first and second hydration shells. The simulations showed a highly flexible first shell, with coordination numbers fluctuating between 6 and 8 and an average Hg–O distance of 2.38 Å, consistent with neutron diffraction and X‐ray absorption benchmarks. The mean residence time of first‐shell water molecules is ∼2 ps, indicating rapid ligand exchange events over the present sampling window. The vibrational density of states derived from the Hg–O velocity autocorrelation function exhibits a broad maximum at 301 , reflecting fast structural fluctuations of the hydration environment. Overall, the SCAN–QMCF MD results provide a balanced description of coupled structural disorder and exchange dynamics of hydrated within a long‐timescale simulation.
Niko Prasetyo (2026) studied this question.