Structural evolution and molecular dissociation of H2S under high pressures

Abstract

Solid H2S as the precursor for H3S with incredible superconducting properties under high pressure, has recently attracted extensive attention. Here in this work, we propose two new phases of H2S with P42/n and I41/a lattice symmetries in a pressure range of 0 GPa–30 GPa through first-principles structural searches, which complement the phase transition sequence. Further an ab initio molecular dynamics simulation confirms that the molecular phase P2/c of H2S is gradually dissociated with the pressure increasing and reconstructs into a new P21/m structure at 160 GPa, exhibiting the superconductivity with T c of 82.5 K. Our results may provide a guidance for the theoretical study of low-temperature superconducting phase of H2S.