Structure of liquid SnSe under pressure

Introduction IV-VI compounds are regarded as average group V material. In crystalline group V elements and IV-VI compounds, the Peierls distortion occurs. Strong bonds with short bond length and relatively weak bonds with long bond length coexist in the crystal. Therefore anisotropic contraction of the local structure is expected under pressure [1]. In crystalline SnSe, atoms form two dimensional networks of covalent bonds with coordination number of three at the normal pressure. No pressure-induced transition in the crystalline phase has been reported. In liquid SnSe, the local structure at the normal pressure is known to be similar to that of crystalline phase: The coordination number is about three and layer structure remains upon melting [2]. On the other hand, the local structure of liquid GeSe and liquid GeTe and its pressure dependence are different from those of the crystalline phase [3].