Calculated optical and structural properties of InP under pressure

Self-consistent linear muffin-tin orbital band-structure calculations are used to investigate the optical and structural properties in InP under pressure. The assignments of the structures in the dielectric functions and the band-structure critical-point transitions are presented and compared with new ellipsometric measurements. A new assignment is proposed for the structure commonly labeled $E_0^{\mathcal{’}}$+${\Delta }_0^{\mathcal{’}}$. The calculated linear and nonlinear pressure coefficients of the energy gaps at high-symmetry points agree well with experimental data and other theoretical results. The value of the pressure at the crossover from the direct to the indirect gap is found to be 10.4±0.2 GPa in the assumed zinc-blende structure, whereas the transition to the metallic phase (rocksalt structure) is determined to occur at 9.8 GPa. These results confirm recent experimental suggestions that there is no evidence of the Γ-X crossover up to the observed phase-transition pressure.