Our second publication of 2021 “First-principles investigation of electronic, optical, mechanical and heat transport properties of pentadiamond: A comparison with diamond” has just appeared in Carbon Trends
Pentadiamond is a carbon allotrope consisting of hybrid sp2 and sp3 atoms, which has recently been predicted to be stable and synthesizable. We employed first-principles calculations to explore the electronic structure, optical characteristics, mechanical response and lattice thermal conductivity of pentadiamond, performing a direct comparison with the corresponding properties in diamond. Density functional theory calculations with the HSE06 functional predicts indirect electronic band gaps of 3.58 eV and 5.27 eV for pentadiamond and diamond, respectively. Pentadiamond shows large absorption in the middle UV region, where diamond does not absorb light, consistent with its smaller band gap. The elastic modulus and tensile strength of pentadiamond are 496 GPa and 60 GPa, respectively, considerably lower than the corresponding values for diamond. Finally, the lattice thermal conductivity was examined by solving the Boltzmann transport equation with anharmonic force constants evaluated via state-of-the-art machine-learning interatomic potentials. We predict a thermal conductivity of 427 W/m-K for pentadiamond, less than one fifth of the corresponding quantity for diamond. Our results provide a useful vision of the intrinsic properties of pentadiamond, but also highlight some of its disadvantages in mechanical strength and heat conduction when compared to diamond.
This work results from collaboration with colleagues at Leibniz Universität Hannover and the Persian Gulf University.