A DFT Investigation of the Electronic and Optical Properties of Pentadiamond

Recently, a new carbon 3D carbon allotrope named pentadiamond was proposed. Pentadiamond is composed of carbon atoms in mixed sp$^2$ and sp$^3$-like hybridization. In this work, we have carried out a detailed investigation of the electronic and optical properties of pentadiamond structure using first-principles (DFT) methods. Our results show that pentadiamond has an indirect bandgap semiconductor of $2.50$ eV with GGA-PBE and $3.31$ eV with HSE06. Its static dielectric constant is $4.70$ and the static refractive index is $2.16$. Pentadiamond presents low reflectivity, almost 40$\%$, for all-optical spectrum, making it a good structure to be used as a UV collector. Also, pentadiamond exhibits optical activity in the UV range where other carbon allotropes, such as diamond and 8-tetra(2,2) tubulane show no activity.