DFTB Parametrization at the Example of Platinum-Implementation, Validation and Practical Considerations

Practical considerations for the parametrization of the transition metal platinum within the third-order density-functional tight-binding (DFTB3) method are presented, enabling straightforward parametrizations of interactions between Pt and elements from the s-, p-, and d-blocks of the periodic table. The newly developed parameter set is fully compatible with the 3ob DFTB3 framework, thereby extending the chemical space accessible to DFTB and enabling rapid and reliable simulations of platinum-containing systems. The parameters were initially benchmarked against more than 1300 Pt-containing structures extracted from the Cambridge Crystallographic Data Centre, as well as over 50 reference systems optimized at the MP2/cc-pVTZ level of theory. Further validation included a challenging binuclear platinum(II) complex, QM/MM molecular dynamics (MD) simulations of Pt(II) complexes in aqueous solution, and 3d-periodic DFTB-based molecular dynamics simulations of cisplatin embedded in metal-organic framework (MOF) hosts. Analysis of the resulting trajectories demonstrates a robust and consistent description of platinum coordination environments. To facilitate reproducibility and adoption, example Python scripts covering each step of the parametrization workflow are provided as part of the Supporting Information.