Structural, electronic, optical and vibrational properties of CdSiP2 from first-principles.

We report the results of a first-principles research of the structural, electronic, linear and nonlinear responses, and vibrational properties of CdSiP 2 based on the density functional theory using pseudopotential plane-wave approach. We calculate the energy band structure, dielectric function, absorption coefficient, reflectivity, refractive index, SHG susceptibility, and phonon dispersion curves. In order to obtain accurate band gap value of CdSiP 2 , the GW approximation method is used to calculate the quasiparticle band structure and the corrected band gap value is in excellent agreement with experimental measurements. Furthermore, the corrected band gap can be used as scissor shift for linear and nonlinear optical properties calculations. The linear-response theory is used to derive the phonon dispersion curves and density of states. All zone-center phonon modes are calculated and LO-TO splitting of the infrared modes are identified. The results show a good agreement with available experimental data and other calculations. • The band gap due to the GW correction is used as scissor shift to calculate the optical properties. • We evaluate the dielectric function for different optical polarizations. • The refractive index data show that CdSiP 2 crystal has a negative birefringence as expected. • The intra-(2 ω)/(1 ω) and inter-(2 ω)/(1 ω) band contributions to the imaginary part are presented. • The phonon frequencies at the Brillouin zone center are calculated. [ABSTRACT FROM AUTHOR]