Exhaustive DFTB Parameterization and Its Implementation for the Exploration of Ag Nanostructures + H₂O Complexes

To describe Ag-H₂O hybrid systems, a new SCC-DFTB parameterization is introduced by generating Ag-X, O-X, and H-X (X = Ag, O, H) pair parameters using the density functional-based tight binding (DFTB) module in Materials Studio 2020. We verify the accuracy of the parameters designated as DFTB-AgOH by juxtaposing them with the outcomes of DFT-DMOL3 and DFTB-HYB for several Ag systems, including clusters (n = 2, 4, 6, 11, 17, 22), monolayer surfaces (n = 9, 16, 25, 37, 49), a bilayer (Ag₅₀), and Ag-H₂O complexes. The new parameters align closely with DFT-DMOL3 for morphology, energy, and electronic properties. They also outperform DFTB-HYB, which frequently produces anomalous surface structures. DFTB-AgOH effectively optimizes extensive Ag surfaces and forecasts stable configurations for Ag-H₂O systems, closely resembling the findings of DFT. DFTB-AgOH and DFT-DMOL3 both predict analogous adsorption sites for water molecules on silver nanostructures. Nevertheless, the hydrogen orientation is frequently flipped, indicating that this parameterization lacks precision. We employ two linear scaling equations, Y = -0.096 X - 12.998 (adsorption energy) and Y = -0.143 X - 15.383 (interaction energy), to correlate DFTB-AgOH data with DFT-DMOL3 values. This enables us to identify trends and assess the compatibility of the two systems across various sizes. The activation energies for water dissociation from DFTB-AgOH and DFT-DMOL3 are in strong agreement. Molecular dynamics simulations indicate that the dynamic behavior forecasted by DFTB-AgOH aligns more closely with DFT-DMOL3 than with DFTB-HYB, particularly for temporal variations.