Pressure effect on the electronic and optical properties of the FeP2 and FeAs2 compounds

• Pressure effect on electronic and optical properties of FeP2 and FeAs2 is carried out.
• Equation of state pressure–volume has been calculated.
• The pressure coefficients for the gaps are predicted.
• The dielectric tensor elements decrease with pressure for both compounds.

First principles calculations, by means of the full potential linearized augmented plane wave method within the local density approximation, were carried out for the pressure dependence of the electronic and optical properties of the orthorhombic compounds FeP2 and FeAs2. The variation of the energy gaps has the same trend in both compounds. All the first order band gap pressure coefficients are positive except the T−TT−T one in FeP2 and the one corresponding to smallest indirect gap which are negative. The structures in the optical spectra shift towards higher energies when pressure increases. The static dielectric components decrease with pressure and show anisotropic behavior.