Tuning the electronic and vibrational properties of Sn2P2S6: Pressure induced metallization and superconductivity

Abstract

The influence of external pressure on the properties of Sn2P2S6 has been systematically studied using density-functional theory calculations. It has been found that the ambient-pressure polymorph (space group P21/c) is most stable up to 100 GPa than the other two polymorphs reported in the literature. We have also found that the electronic band gap closes under compression, being metallization achieved at 35 GPa. In addition, electron–phonon coupling calculations show that the studied material is a superconductor at pressures of 35 GPa and higher. The critical temperature increases under compression. We will also present results on phonon-dispersion calculations, showing that Sn2P2S6 becomes dynamically unstable near 60 GPa. Finally results on the linear and volumetric compressibility are reported showing that Sn2P2S6 is highly compressible with a bulk modulus of 34(1) GPa.

Keywords

• Superconductivity
• Electron–phonon coupling
• Electronic structure
• High pressure