Abstract: The geometric parameters and the electric and optical properties of β-FeSi2 are calculated using first principle methods based on plane-wave pseudo-potential theory in detail. The results indicate that:(1) β-FeSi2 is a quasi-direct semiconductor and the band gap is 0.74eV.The density of states is mainly composed of Fe 3d and Si3p.(2) The valences electronic state of β-FeSi2 is asymmetric and has a strong local area characteristic.These have an important influence on the electronic structure and the bonding characteristics of β-FeSi2.(3) The calculation of the dielectric function reveals that β-FeSi2 is anisotropic,the biggest peak of absorption is 2.67e5cm-1,the extinction coefficient shows strong absorption characteristic near the band edge,and the mechanism of the electric and optical properties of β-FeSi2 dominated by electron inter-band transitions are analyzed in terms of calculated band structure and density of states.

Key words: β-FeSi2, electronic structure, optical properties