The structural, electronic, optical, and mechanical properties of carbon-based halides: An ab initio DFT approach

In the present work, we choose the carbon-based halides CX4 (X = Br, Cl) to conduct a study on the ground-state properties using first-principles calculations based on density functional theory. We provide a comparative study for bromide and chloride materials using standard generalized gradient approximation functionals. A total of 80 atoms have been simulated on a single unit cell. A direct bandgap energy of 3.28 (4.64) eV for X = Br (X = Cl) with Z–Z transition is found on the studied materials. According to our partial density of states plot, a hybridization of s orbitals on C and X atoms is observed. Metallic properties have also been identified. A low reflectivity of 6% (12%) has been measured, which presents excellent material absorption. Such a material is also determined to be brittle, based on the calculated Pugh’s ratio. The reflectivity (ductility) tends to increase as the X element increases down the Period Table. The negative Poisson’s ratio found also suggests that the materials could be used as an electrode for metal-ion (e.g., Li, K, and Na) batteries.