Binding Free Energy Calculations of Bilayer Graphenes Using Molecular Dynamics

Area of Science:

• Materials Science
• Computational Chemistry
• Nanotechnology

Background:

• Bilayer graphenes are formed by two graphene layers linked by π-complexation.
• Controlling bilayer graphene assemblies is challenging due to aggregation and dispersion.
• Understanding inter-layer interactions is crucial for material stability.

Purpose of the Study:

• To investigate the dissociation dynamics and binding energies of bilayer graphenes.
• To analyze the direction-dependent nature of bilayer graphene dissociation.
• To assess the influence of bilayer graphene size on dissociation pathways and stability.

Main Methods:

• Pulling molecular dynamics simulations were employed to study bilayer graphene dissociation.
• Normal and shear force profiles were obtained to characterize dissociation forces.
• Umbrella sampling simulations were used to calculate binding free energies.

Main Results:

• Bilayer graphene dissociation is direction-dependent, differing between normal and shear pathways.
• Consistent binding free energies were observed along the shear direction across different sample sizes.
• Dissociation along the normal direction is less adiabatic, with a significant entropic contribution to Gibbs energy, enhanced in larger bilayer graphenes.

Conclusions:

• The study elucidates the complex dissociation mechanisms of bilayer graphenes.
• Directionality and size significantly influence the stability and energetic landscape of bilayer graphene systems.
• Findings provide insights into the fundamental interactions governing layered graphene materials.