First-principle calculations to investigate structural, electronic, optical, elastic, and phonon properties of carbon-based IV compounds (Ge, Sn) with hybrids

Abstract

We investigated the electronic, optical and mechanical properties of cubic Germanium Carbide (GeC) and Tin Carbide (SnC) using Density Functional Theory (DFT). Our calculations yielded a lattice length of a = 3.27 Å (3.47 Å) and a bond angle of α = 60° for the primitive cell lattice. The bulk GeC and SnC exhibited indirect bandgaps of 2.33 eV and 1.74 Ev, respectively. Analysis of the density of states plot revealed hybridization between C 2p² and Sn 5p² (Ge 4p²) orbital states. Mechanical property calculations indicated that these carbon-based compounds are brittle and covalent in nature, as suggested by Pugh's ratio. The isotropic nature of the material was confirmed by the identical Young's modulus (E) values in all three directions. We also calculated the group velocity for bulk carbon-based materials and compared these values with their monolayer counterparts. Finally, dynamical stability was verified since all phonon branches exhibited positive frequencies.