Density functional study of structural and optoelectronic properties of SnTe: rocksalt and orthorhombic phases

In this work, we perform first-principles computations on the structural, electronic, optical and transport properties of the rocksalt and orthorhombic phases of SnTe. Previous experimental and theoretical results have shown good correlation with the optimized lattice parameters of SnTe in both phases. All the calculations are performed based on the density functional theory (DFT) with the generalized gradient approximation (GGA) and modified Becke-Johnson (mBJ) exchange-correlation potentials. The electronic structure calculation using the mBJ potential reveals a direct band gap in the rocksalt phase which decreases when spin-orbit coupling is incorporated, while a semi-metallic behavior is observed in the orthorhombic phase. Optical properties including dielectric function, absorption, reflectivity, etc. are analyzed showing significant phase-dependent variations with spin-orbit coupling having a noticeable effect at lower energies. Additionally, transport property analysis indicates that the orthorhombic phase has better thermoelectric performance making SnTe a promising material for optoelectronics and energy applications.