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Graphene Growth on Copper Substrate by LAMMPS Simulation

Lizhe Hong

TL;DR

This study tackles the challenge of modeling graphene growth on a Cu(111) substrate using LAMMPS MD, addressing prior issues of runaway pressure and incomplete potential-function choices. It implements a corrected, multi-potential framework with a three-region thermostat and non-periodic boundaries to stabilize deposition dynamics, depositing methane-derived carbon as C1/C2 onto Cu(111) and relaxing the substrate via cg minimization. The results reveal that graphene nucleation and layer formation are strongly temperature-dependent, with the best growth quality and carbon utilization observed around $T\approx 1300$ K, where 5-6 member rings form more stably and islands coalesce into continuous layers. The work provides a detailed potential-function selection table and a reproducible MD workflow for simulating 2D material growth on metal substrates, enabling more reliable predictions for graphene synthesis via methane cracking in CVD-like contexts.

Abstract

We learned the atomic deposition simulation of LAMMPS independently, referenced and optimized the modeling ideas of several papers, used the (1 1 1) crystalline surface of Cu atoms as a substrate, deposited C atoms produced by methane cleavage to obtain graphene flakes, and analyzed the deposition rate and deposition quality at three temperatures, obtaining conclusions consistent with the process flow. We found that there were obvious problems in previous papers. After a certain period, the overall system pressure became excessively high, causing simulation crashes and preventing analysis of subsequent results. In addition, understanding of potential function selection was incomplete. Therefore, after correcting these issues, a simulation system with relatively stable pressure was constructed. In addition to the result analysis, a potential-function selection table is provided, with some parameters taken from prior experimental calculations and others obtained via DFT calculations.

Graphene Growth on Copper Substrate by LAMMPS Simulation

TL;DR

This study tackles the challenge of modeling graphene growth on a Cu(111) substrate using LAMMPS MD, addressing prior issues of runaway pressure and incomplete potential-function choices. It implements a corrected, multi-potential framework with a three-region thermostat and non-periodic boundaries to stabilize deposition dynamics, depositing methane-derived carbon as C1/C2 onto Cu(111) and relaxing the substrate via cg minimization. The results reveal that graphene nucleation and layer formation are strongly temperature-dependent, with the best growth quality and carbon utilization observed around K, where 5-6 member rings form more stably and islands coalesce into continuous layers. The work provides a detailed potential-function selection table and a reproducible MD workflow for simulating 2D material growth on metal substrates, enabling more reliable predictions for graphene synthesis via methane cracking in CVD-like contexts.

Abstract

We learned the atomic deposition simulation of LAMMPS independently, referenced and optimized the modeling ideas of several papers, used the (1 1 1) crystalline surface of Cu atoms as a substrate, deposited C atoms produced by methane cleavage to obtain graphene flakes, and analyzed the deposition rate and deposition quality at three temperatures, obtaining conclusions consistent with the process flow. We found that there were obvious problems in previous papers. After a certain period, the overall system pressure became excessively high, causing simulation crashes and preventing analysis of subsequent results. In addition, understanding of potential function selection was incomplete. Therefore, after correcting these issues, a simulation system with relatively stable pressure was constructed. In addition to the result analysis, a potential-function selection table is provided, with some parameters taken from prior experimental calculations and others obtained via DFT calculations.

Paper Structure

This paper contains 12 sections, 3 equations, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. Computational Method
  3. Growth Environment Setup
  4. Potential function
  5. Thermodynamic setup and Particle update method
  6. Results and Discussion
  7. Radius of gyration and visual representation of C2
  8. Explanation based on perturbation theory
  9. Graphene Growth and Layer Formation
  10. Rate of adsorption of C atoms
  11. Conclusion
  12. Acknowledgments

Figures (3)

  • Figure 1: Structure of the simulated system: red atoms are Cu atoms, blue atoms are C1 atoms, yellow atoms are C2 atoms.
  • Figure 2: Top views of the overall system at different temperatures and other relevant distributions. (a) 900 K, (b) 1100 K, (c) 1300 K. (d) time-swing radius distribution images. (e) time-deposited atom number distribution images. (f) In t=500 ps, number of five-membered rings. (g) ratio of five-membered rings to C atoms in the total deposited region.
  • Figure 3: (a) Because of the Langevin heat bath, the high-temperature Cu atoms pull the already adsorbed C atoms to hit the C atoms that are not adsorbed with the Cu atoms, thus causing the C atoms to fly out, where the red arrows represent the amplitude of the movement of the Cu atoms at lower temperatures, and the blue arrows represent the amplitude of the movement of the Cu atoms at higher temperatures. (b) Potential energy curve image, the horizontal axis represents the distance between C atoms, and the vertical axis represents the potential energy, showing the reason why C atoms grow densely at high temperatures.