Interaction between benzenedithiolate and gold: classical force field for chemical bonding

Area of Science:

• Computational Chemistry
• Materials Science
• Surface Science

Background:

• Accurate classical potentials are crucial for simulating molecular behavior at interfaces.
• Density-functional theory (DFT) provides a robust framework for calculating electronic structure and bonding properties.

Purpose of the Study:

• To develop classical potentials for benzenedithiolate (BDT) and gold interactions using DFT.
• To investigate the influence of different DFT functionals on bonding parameters and molecular configurations.
• To analyze the structure of BDT self-assembled monolayers (SAMs) and adatom adsorption on gold surfaces.

Main Methods:

• Ab initio DFT calculations using LDA, PBE0, and X3LYP functionals.
• Calculation of single point energies (SPE) for various BDT-Au complex configurations.
• Mulliken population analysis to determine atomic charge variations.
• Molecular-dynamics (MD) simulations for BDT SAM structure and S adatom adsorption on Au (111).

Main Results:

• DFT methods yielded similar bonding curves for BDT-Au interactions.
• Mulliken partial charges in BDT were found to be stable across configurations, reducing simulation uncertainty.
• Bond-stretching potential was identified as the dominant factor in chemical bonding.
• Global BDT SAM packing structure showed independence from DFT functional choice, despite parameter uncertainties up to 100%.

Conclusions:

• Classical potentials based on DFT accurately describe BDT-gold chemical bonding.
• Intermolecular interactions are the primary drivers of the global packing structure in BDT SAMs.
• The choice of DFT functional has a limited impact on the overall SAM structure.