Pressure induced, electronic and optical properties of zincblende InP

We have investigated the electronic and optical properties of zincblende InP at ambient and under hydrostatic pressure using the full potential linear augmented plane wave (FP-LAPW) method. The pressure dependence of the energy gaps along different symmetry directions have been found to obey the equation Eg(p)=Eg0+ap+bp2. The pressure coefficients are in agreement with experiment. The valence bandwidth increases with increasing pressure which results in increased covalent character. The optical properties have been calculated and compared with ellipsometric measurements. The variation of band gaps with respect to the application of pressure and the origin of structures in the optical spectra are discussed in terms of the band structure.