Recently, Prof. Jianfei Liu’s group published online an article entitled “An Automatic Method for Generating Carbon Nanostructure Atomistic Models using Hexagonal Meshes with Properly Distributed Defects” in the International Journal for Numerical Methods in Engineering, a top journal in the area of computational mechanics.
Based on FEM triangulation techniques, this article proposed an automatic modeling algorithm for arbitrary carbon nanostructures and developed a fast, efficient and accurate automatic modeling tool. This technique has obvious advantages over present subjective, inefficient and heavy manual modeling way and will be a powerful tool for researchers in related areas.
Figure 1: An automatic modeling tool for carbon nanostructures based on triangular mesh generation and optimization techniques. Nanotube-derived carbon foam modeling via our modeling tool: (a) design a 3D model; (b) generate triangular meshes via the sphere-packing method; (c) optimize the mesh to reduce its irregular vertices (valences other than six); (d) obtain dual quasi-hexagon meshes (carbon nanostructure atomistic model) from triangular meshes; (e) magnified view.
Numerical simulation methods such as the molecular dynamics (MD) simulation are indispensable approaches for studying carbon nanostructures. Modeling is the primary step in numerical simulation methods. Currently, atomistic models are created mostly by hand, though there are packages which can automatically generate simple atomistic models. As the research on nanomaterials continues to develop and its applications continue to extend, increasingly complicated carbon nanostructures are designed theoretically or discovered in the laboratory. More efficient tools are strongly expected.
Taking physical and geometrical characteristics of carbon nanostructures into consideration, Liu’s group innovatively introduced FEM mesh techniques into carbon nano field, changing carbon nanostructure modeling problem into quasi-hexagon mesh problem. Main idea of this modeling algorithm is as following(shown as Figure 1):(1)use CAD software to describe geometry of carbon nanostructure; (2)triangulate the 3D curved surface with spere-packing method; (3)optimize original trangulation and convert optimized triangulation into quasi-hexagon mesh (atomistic model of carbon nanostructure).
Three examples indicate the tool’s capability: 1) Complex tube structures composed of lots of nanotubes shown as fig.1; 2) polycrystalline graphene composed of differently angled graphene shown as fig. 2; 3) arbitrary structure composed of graphene, fullerene, nano-cone and nanotube shown as fig. 3.
Figure 2: There types of polycrystalline graphene.
Figure 3: Combination of four kinds of nanostructures.
Two joint first authors of this article are Dr. Feifei Shang and Ms. Zhen Zen. Ms. Tingfei Chen, once an intern in Liu’s group, has her contribution in this work too.