Using the density functional theory in the local density approximation the pressure dependence of the structural, dynamical, and electronic properties of the $\mathrm{Sn}{\mathrm{P}}_2{\mathrm{S}}_6$ layered semiconductor in the pressure range up to $35\mathrm{GPa}$ is investigated. The pressure dependence of the lattice parameters is well described by the Murnaghan equation of state. The nonmonotonic pressure dependence of the structural polarization is obtained. The $\mathrm{Sn}{\mathrm{P}}_2{\mathrm{S}}_6$ compound is predicted to be an indirect-gap semiconductor. At a pressure of above $10\mathrm{GPa}$, an indirect-direct bandgap crossover is observed. The pressure dependence of the long-wavelength lattice vibration frequencies is calculated and compared with experimental results from Raman spectroscopy in the pressure range $0–21.5\mathrm{GPa}$. Full phonon dispersion curves do not indicate mode softening over the entire range of the Brillouin zone. The stability of the structure under pressure is discussed.

• Received 26 March 2004

DOI:https://doi.org/10.1103/PhysRevB.73.115115