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

Area of Science:

• Computational Materials Science
• Quantum Chemistry
• Surface Science

Background:

• Accurate modeling of silver-water (Ag-H2O) hybrid systems is crucial for understanding surface interactions and catalytic processes.
• Existing computational methods, such as Density Functional Theory (DFT) and simplified DFTB (Density Functional-based Tight Binding) approaches, have limitations in describing these systems efficiently and accurately.
• The development of reliable and computationally efficient parameterizations is needed for large-scale simulations of Ag-H2O interactions.

Purpose of the Study:

• To introduce and validate a new SCC-DFTB parameterization, termed DFTB-AgOH, for Ag-H2O hybrid systems.
• To assess the accuracy of DFTB-AgOH by comparing its predictions with established DFT-DMOL3 and an alternative DFTB-HYB method.
• To evaluate the performance of DFTB-AgOH in optimizing silver surfaces and predicting stable Ag-H2O configurations.

Main Methods:

• Generated new Ag-X, O-X, and H-X (X = Ag, O, H) pair parameters for SCC-DFTB using Materials Studio 2020.
• Validated the DFTB-AgOH parameters by comparing results for various silver systems (clusters, monolayers, bilayer, Ag-H2O complexes) against DFT-DMOL3 and DFTB-HYB.
• Employed linear scaling equations to correlate DFTB-AgOH and DFT-DMOL3 data for adsorption and interaction energies, and performed molecular dynamics simulations.

Main Results:

• DFTB-AgOH demonstrates high accuracy in predicting morphology, energy, and electronic properties of silver systems, closely matching DFT-DMOL3.
• DFTB-AgOH outperforms DFTB-HYB, which exhibits anomalous surface structures, and effectively optimizes large silver surfaces and Ag-H2O systems.
• Both DFTB-AgOH and DFT-DMOL3 identify similar water adsorption sites on silver nanostructures, though hydrogen orientation shows discrepancies; activation energies for water dissociation are in strong agreement.

Conclusions:

• The new DFTB-AgOH parameterization provides a reliable and computationally efficient tool for studying Ag-H2O hybrid systems.
• DFTB-AgOH accurately predicts structural, energetic, and dynamic properties of silver nanostructures and their interactions with water.
• This parameterization enables large-scale simulations and offers insights into water adsorption and dissociation on silver surfaces, complementing DFT results.