Abstract
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 $35\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ 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 $10\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, 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 $0--21.5\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. 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.
Published Version
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