Integrated Spectroscopic and First-Principles Study of Dirac Semimetal Cd₃As₂

This study presents an integrated experimental and theoretical analysis of the Dirac semimetal Cd₃As₂, combining bulk crystal growth through chemical vapor transport (CVT) and congruent melt methods with single-crystal structural and spectroscopic characterization. In parallel, first-principles calculations based on density functional theory (DFT) and time-dependent DFT (TDDFT), incorporating spin-orbit coupling (SOC), are employed to complement the experimental findings. The computed electronic band structures confirm the inversion of Cd 5s and As 4p orbitals, revealing the formation of Dirac nodes upon including SOC. Orbital-resolved density of states (DOS) offers insight into the atomic orbital contributions near the Fermi level, enhancing the understanding of the low-energy electronic structure of Cd₃As₂. Additionally, the computed optical properties, including the frequency-dependent dielectric constants (real ε₁ and imaginary ε₂ parts), refractive index (n), extinction coefficient (k), and reflectivity (R) derived from the susceptibility tensor χ_ij(ω) using turbo-TDDFT, show qualitative agreement with experimental and theoretical benchmarks.