Density-functional theory study of magnetic and electronic properties of KFe2Se2 under pressure

The magnetic properties and electronic structures of KFe2Se2 under pressure were studied by first principles calculations. Five different states of KFe2Se2 were considered, and the ground state of collinear antiferromagnetic state was determined. The calculated results showed when the pressure was increased to 0.36 GPa, the connection between Fe atom and Se atom was strengthened and the magnetic moment was reduced to 0 mu B. A gap appeared in the density of states between-4 eV and-3 eV, and the Fermi surface was greatly reconstructed. The electronic structures of KFe2Se2 under 0.36 GPa were similar to that of nonmagnetic KFe2Se2, while the stability of the system was not changed obviously. The results indicate that the evolution at the critical pressure 0.36 GPa was worthy of further study for KFe2Se2.