Stillinger–Weber potential for elastic and fracture properties in graphene and carbon nanotubes

Abstract

This paper presents a new framework for determining the Stillinger-Weber (SW) potential parameters for modeling fracture in graphene and carbon nanotubes. In addition to fitting the equilibrium material properties, the approach allows fitting the potential to the forcing behavior as well as the mechanical strength of the solid, without requiring ad hoc modification of the nearest-neighbor interactions for avoiding artificial stiffening of the lattice at larger deformation. Consistent with the first-principles results, the potential shows the Young's modulus of graphene to be isotropic under symmetry-preserving and symmetry-breaking deformation conditions. It also shows the Young's modulus of carbon nanotubes to be diameter-dependent under symmetry-breaking loading conditions. The potential addresses the key deficiency of existing empirical potentials in reproducing experimentally observed glass-like brittle fracture in graphene and carbon nanotubes. In simulating the entire deformation process leading to fracture, the SW-potential costs several factors less computational time compared to the state-of-the-art interatomic potentials that enables exploration of the fracture processes in large atomistic systems which are inaccessible otherwise.

Effect of Angle, Temperature and Vacancy Defects on Mechanical Properties of PSI-Graphene

“…According to the characteristics of PSIgraphene and graphene sheets, the range between 0° and 180° was observed in Figure 3a,b, and the The mechanical properties of PSI-graphene and graphene can be described by two independent constants, i.e., ultimate strength and Young's modulus. According to the characteristics of PSI-graphene and graphene sheets, the range between 0 • and 180 • was observed in Figure 3a,b, and the range between 0 • and 30 • was observed in Figure 3c, [36]. The Young's modulus was reduced by about 12.6%.…”

“…The Young's modulus was 1033 GPa at 0°. The Young's modulus had a minimum in the direction of 0°, 60°, 120°, 180°, 240° and 300°, which was 903 GPa [36]. The Young's modulus was reduced by about 12.6%.…”

Magic auxeticity angle of graphene

“…Each sample has a similar size of about 200Å×200Å and consists of about 16,000 carbon atoms. These configurations are selected to ensure that the system size has trivial effects on the results [21]. Details about the graphene samples are summarized in Table 1 of the supplementary materials. For all the simulations, the time step was set at 0.00025 ps and the Newton's equation of motion were numerically integrated using the velocity-Verlet algorithm [22].…”

Buckling Analysis of Single-Layer Graphene Sheets Using Molecular Mechanics

“…Among them, ab-initio simulations (Kudin et al, 2001;Baumeier et al, 2007;Liu et al, 2007) are the most accurate tools available to investigate the behavior of nanomaterials, including their mechanics, but they demand a lot of computer power and so they are not always feasible for systems with very many atoms. For this reason, increasing attention has been given to molecular dynamics/statics formulations (Liew et al, 2004;Lu et al, 2009;Xiao et al, 2009;Zhao et al, 2009;Georgantzinos et al, 2012;Silvestre et al, 2012;Berinskii and Borodich, 2013;Davini, 2014;Theodosiou and Saravanos, 2014;Gamboa et al, 2015;Korobeynikov et al, 2015Korobeynikov et al, , 2018Budarapu et al, 2017;Davini et al, 2017;Genoese et al, 2017Genoese et al, , 2018aGenoese et al, ,b, 2019Hossain et al, 2018;Sgouros et al, 2018;Singh and Patel, 2018b) or their structural-mechanical approximations (e.g., nanoscale equivalent beam and truss models; Sakhaee-Pour, 2009a,b;Georgantzinos et al, 2010;Alzebdeh, 2012;Giannopoulos, 2012;Tserpes, 2012;Firouz-Abadi et al, 2016;Rafiee and Eskandariyun, 2017;Savvas and Stefanou, 2018) and to continuum models (Chang, 2010;Aminpour and Rizzi, 2016;Ghaffari et al, 2018;Singh and Patel, 2018a;Zhang et al, 2018).…”

“…Most of the research on graphene has focused on its rigidities, the frequencies of free vibration, and tensile failure properties and this has produced also a refinement of the parameters of simple bonding potentials (Genoese et al, 2017;Hossain et al, 2018;Korobeynikov et al, 2018), such as the DREIDING, the Stillinger-Weber or the modified Morse potentials. Currently, molecular statics formulations based on these potentials are considered to be the best compromise at the atomistic scale in non-linear contexts, where the simplicity of the models is a major requirement.…”