Density functional study of the structural, phonon, elastic and optical properties of hexagonal SnS2

The mechanical, electronic, optical and lattice dynamic properties of SnS₂ were studied by first-principles calculations within the pressue range of 0–32 GPa. The phonon spectra and elastic constants confirm the stability of crystal structure for SnS₂. Additionally, the pressure dependence of key elastic properties—such as bulk modulus (B), shear modulus (S), Young's modulus, B/G ratio, and Poisson's ratio—was analyzed. The results indicate that SnS₂ exhibits lower hardness and enhanced ductility and plasticity at higher pressures. The vibrational characteristics were also investigated under hydrostatic conditions up to 32 GPa, with a focus on in-plane (shear) and out-of-plane (breathing) modes in the low-frequency region. The vibrational behavior of the constituent ions in these modes was further explored. Furthermore, the optical properties reveal that SnS₂ strongly absorbs both visible and ultraviolet light.