Using the first-principles method based on density functional theory we study the structural properties of zinc-blende structure,rocksalt structure and hexagonal wurtzite structure of ZnSe.At the same time,according to the isoenthalpy principle,we have found the transition pressure from zincblende to rocksalt is about 15.5 GPa,which is in good agreement with the experimental result.The elastic constants of ZnSe with zinc-blende structure under different pressures are calculated.The relationship between the ...