A tetragonal high-pressure phase of PtAs2

A tetragonal high-pressure phase of PtAs2 with I4/mmm symmetry was first discovered above 90 GPa by using first principle swarm intelligence structure search technique. The first order structure transition character of PtAs2 from the ambient-pressure cubic pyrite phase to this tetragonal HP phase was confirmed by a large volume reduction of 8.1%. During structure transition, the independent As2 dimers in the pyrite phase were twisted and connected with each other under compression to form three-dimensional As puckered networks in the tetragonal HP phase, accompanied by the increase of the coordination of Pt from 6 to 8. Compared to the semiconducting pyrite phase, the metallic feature of this tetragonal HP phase has been demonstrated by the electronic structure analyses.