Mechanical Properties of Pentadiamond—A Combined DFT and Reactive Molecular Dynamics Investigation

Recently, a new carbon allotrope called pentadiamond was proposed [1]. It consists of a network of pentagonal rings where both sp2 and sp3 hybridization are present. Recent works have shown that pentadiamond presents thermoelectric and optoelectronic [1,2] properties. 3D-printed pentadiamond structures [3] also exhibit the same topology-dependent mechanical behavior of the atomic model. In this work [4], we investigated the mechanical and electronic properties and the thermal stability of pentadiamond using DFT and fully atomistic reactive molecular dynamics (MD) simulations. The mechanical behavior, beyond the elastic regime, was investigated for three deformation modes: compression, tensile, and shear. Under compressive deformation, strong fluctuations in the atomic positions appear, which are responsible for the strain-softening at strains beyond the linear regime. These characterize its plastic flow. As expected, as we increase temperature, Young’s modulus values decrease, with changes (up to 300 K) smaller than 10% (from 347.5 to 313.6 GPa). The fracture strain values present a broader variation, from ∼44% at 1K to ∼5% at 300K.<br/><br/>[1] Y. Fujii, M. Maruyama, N. T. Cuong, and S. Okada, Phys. Rev. Lett. 125, 016001 (2020).<br/>[2] R.M. Tromer, L.C. Felix, C.F. Woellner, D.S. Galvao, Chemical Physics Letters, 763, 138210 (2020).<br/>[3] L.C. Felix, R.S. Ambekar, C.F. Woellner, B. Kushwaha, V. Pal, D.S. Galvao and C.S. Tiwary, arXiv:2105.10000 (2021)<br/>[4] L.C. Felix, R.M. Tromer, C.F. Woellner, C.S. Tiwary and D.S. Galvao, Physica B: Condens. Matter Physica B: Condensed Matter 629, 413576 (2022)