International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 07 | Jul 2025
p-ISSN: 2395-0072
www.irjet.net
A Molecular Dynamics Study of Energy Minimization in Mono- and Bilayer Graphene Structures Tatva Kabat¹ 1The Academy for Math, Science, and Engineering, Rockaway, New Jersey, USA
---------------------------------------------------------------------***--------------------------------------------------------------------to graphene’s high aspect ratio and two-dimensionality, it Abstract - In current materials science research, graphene
can also be used as a building block for other carbonbased nanostructures like fullerenes or carbon nanotubes [4]. Graphene’s wide range of applications like highperformance composites and flexible electronics are all rooted in its atomic configuration, which has led to various research efforts trying to understand graphene’s structural stability under various conditions.
remains at the forefront of current studies due to its potential applications in future healthcare, electronics, and construction industries. This study aims to utilize energy minimization in order to determine stable configurations of monolayer and bilayer graphene, showing that altering atomic properties such as bond length and bilayer gap distance would generate more stable configuration of graphene structures, indicated with minimizing the inner potential energy of each graphene structure. By conducting simulations using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), atomic interactions were modeled within graphene structures (all under the AIREBO potential). Graphene structures were visualized using OVITO and plot data extracted from simulation log files via Python. Simulations were tested with varying bond lengths from 1.20-1.70 Å and bilayer gap distances 2.00 Å and 4.00 Å to observe convergence behavior of the structures as they evolved in our simulations. The results confirmed that the optimal bond length for monolayer graphene is approximately 1.42 Å, while bilayer systems consistently minimized to an interlayer spacing near 3.48 Å, with those values aligning with existing theoretical and experimental literature. This study aims to show how changes on the atomic level can greatly enhance the stability of graphene structures and its results can be used to optimize graphene for future applications in nanotechnology and advanced materials science.
As previously mentioned, each carbon atom in a graphene sheet is sp² hybridized, forming three rigid σbonds with adjacent carbon atoms and one π-bond contributing to delocalized electron mobility across the sheet [1,2]. This configuration of atoms creates a symmetrical hexagonal lattice characterized by an ideal C– C bond length of 1.42 Å, a value confirmed through both experimental methods and computational simulations [1,5]. The C-C bond length directly affects both the energetic stability of a graphene system and also its mechanical performance, making it a primary target in energy minimization studies like ours [6,7]. Minor deviations from this ideal bond length of 1.42 Å increase system energy due to bond strain. Defects such as Stone–Wales transformations or vacancies in a graphene sheet further elevate system potential energy and degrade material properties, often by 4.8–7 eV depending on the defect [4,8]. Edge terminations such as hydrogensaturated edges in graphene nanoflakes help reduce total energy and suppress unwanted mid-gap states, since unsaturated or disordered edges destabilize the structure [6].
Key Words: Materials Science, Graphene, Molecular Dynamics, LAMMPS, Energy Minimization
1.INTRODUCTION
These previous research findings show the importance of atomic-scale factors such as bond length, hybridization, edge termination, and defects in graphene’s stability. These basic properties establish the energetic foundation for larger graphene systems, like bilayer graphene, where interlayer spacing and sheet orientation create more complex energetic challenges.
Graphene is a single-atom thick sheet of carbon atoms arranged in a two-dimensional hexagonal lattice, and its physical characteristics such as exceptional electrical and thermal conductivity, mechanical and tensile strength, and optical transmittance make it one of the most researched materials in modern materials science [1,2]. The study of these individual properties have been widely studied since graphene’s isolation in 2004.
Bilayer graphene (BLG) introduces more complexity through interlayer van der Waals (vdW) forces, weak attractive forces between atoms close together, and stacking orientation (how layers are stacked on top of each other). Experimental and computational tests have determined the ideal BLG gap to be around 3.35 Å, found
Due to graphene’s strong in-plane σ-bonds and delocalized π-electrons, formed as a result of the material’s sp² hybridized carbon atoms, it has broad structural and electronic behavior [1,3]. Furthermore, due
© 2025, IRJET
|
Impact Factor value: 8.315
|
ISO 9001:2008 Certified Journal
|
Page 242