Comparing the MP2, DKH2‐MP2 and SCAN Hybrid Forces Molecular Dynamics Simulation on the Structure and Dynamics of Hydrated Ion Ba²⁺ in Aqueous Solution

The study investigated the structural and dynamical properties of hydrated ion Barium (Ba 2+ ) in aqueous solution using quantum mechanical/molecular mechanical molecular dynamics simulations (QM/MM MD simulation). The primary objective was to assess the performance of the SCAN functional in describing the structure and dynamics of formed Ba 2+ hydration shells in aqueous solution. The SCAN/MM MD simulation demonstrated the closest agreement with previously reported experimental data regarding the structural and dynamical properties of hydrated ion Ba 2+ . Specifically, the Ba 2+ and surrounding water molecules distance was determined to be 2.79 Å, with equal distribution of coordination numbers of 8 and 9 in the first hydration shell. Moreover, the stretching frequency of 232.21 cm −1 closely matched the CCSD(T) results. The obtained results from SCAN/MM MD has a better agreement than results from MP2/MM and DKH2 MP2/MM molecular dynamics simulation. These findings underscore the potential of SCAN/MM MD simulation as a promising method for investigating the structural and dynamical properties of hydrated ions.