Optimization of a New Reactive Force Field for Silver-Based Materials.

Area of Science:

• Computational Chemistry
• Materials Science
• Surface Science

Background:

• Reactive force fields (ReaxFF) are crucial for simulating complex chemical systems.
• Accurate modeling of metal-thiolate interactions is essential for nanotechnology and catalysis.
• Previous ReaxFF parametrizations for silver and gold have limitations.

Purpose of the Study:

• To develop and validate a new ReaxFF reactive force field for silver and silver-thiolate systems.
• To improve the accuracy of ReaxFF in describing geometric and energetic properties of silver clusters and surfaces.
• To compare the behavior of silver-thiolate systems with gold-thiolate systems using ReaxFF.

Main Methods:

• Parametrization of a new ReaxFF reactive force field using an extensive dataset of quantum chemistry calculations (>120 structures).
• Simulation of silver clusters (Ag20 pyramid) with adsorbed thiolates.
• Simulation of self-assembled monolayers of thiolates on a silver (111) surface.

Main Results:

• The novel ReaxFF parametrization accurately reproduces average geometric and energetic properties of silver clusters and slabs.
• The model captures the behavior of thiolates adsorbed on silver surfaces.
• Unlike gold-thiolate systems, ReaxFF simulations of self-assembled monolayers on silver (111) did not predict staple formation.

Conclusions:

• The developed ReaxFF reactive force field offers a powerful methodology for accurately simulating silver and silver-thiolate systems.
• This new parametrization improves upon earlier ReaxFF versions for silver and gold.
• The study highlights differences in self-assembled monolayer formation between silver and gold thiolates.