Abstract
Although meta-generalized-gradient approximations (meta-GGAs) are believed potentially the most accurate among the efficient first-principles calculations, the performance has not been accessed on the nonlinear mechanical properties of two-dimensional nanomaterials. Graphene, like two-dimensional silicon carbide g-SiC, has a wide direct band-gap with applications in high-power electronics and solar energy. Taken g-SiC as a paradigm, we have investigated the performance of meta-GGA functionals on the nonlinear mechanical properties under large strains, both compressive and tensile, along three deformation modes using Strongly Constrained and Appropriately Normed Semilocal Density Functional (SCAN) as an example. A close comparison suggests that the nonlinear mechanics predicted from SCAN are very similar to that of Perdew-Burke-Ernzerhof (PBE) formulated functional, a standard Density Functional Theory (DFT) functional. The improvement from SCAN calculation over PBE calculation is minor, despite the considerable increase of computing demand. This study could be helpful in selection of density functionals in simulations and modeling of mechanics of materials.
Highlights
Both elements of carbon and silicon can form mono-elemental 2D crystal structures.Carbon atoms of a graphene mono-layer is coplanar, whereas silicene has a buckled structure
We focus on the generalized gradient approximation (GGA) and the meta-GGA approximation (MGGA) for g-SiC, taking PBE-GGA and Semilocal Density Functional (SCAN)-MGGA as an example
We have assessed the performance of the SCAN calculations on the nonlinear mechanical properties and mechanical stabilities of g-SiC under large strains with point-by-point comparison to that of PBE calculations, including ultimate strength, ultimate strain, 14 non-trivial elastic constants up to 5th order, strain energy profile, stress-strain behaviors, and pressure effect on normal modulus, shear modulus, Poisson ratio, p-wave, s-wave, and velocity ratio, under large deformations in three modes
Summary
Carbon atoms of a graphene mono-layer is coplanar, whereas silicene has a buckled structure. Graphene-like SiC mono-layer (i.e., g-SiC ) is a stable 2D honeycomb structure with a wide indirect band gap (∼2.55 eV) [2]. It is the most thermodynamically stable one among over 300 Six Cy structures [1]. G-SiC has promising applications as blue and ultraviolet light emitted devices (LEDs), and photo-voltaic devices [2,3,4]. It has potential applications in sensors, composites, field emitters, super-capacitors, nanoelectromechanical devices, bioimaging probes, catalysts, field-effect transistors, and wave absorber. Extensive theoretical studies have been done on the structural stability, thermodynamic stability, electronic, catalytic, and optical properties of g-SiC [3,6,7,8,9,10,11,12,13,14,15,16,17,18]
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