Computational study of AgCl and AgBr semiconductors

We present the results of a theoretical study of the structural and optoelectronic properties of silver halides AgCl and AgBr, using the full-potential linearized augmented plane wave (FP-LAPW). In this approach, the local density approximation (LDA) and generalized gradient approximation (GGA) are used for the exchange correlation potential. Moreover, the alternative form of GGA proposed by Engel and Vosko [Phys. Rev. B 47 (1993) 13164] (EVGGA) is also used for the optoelectronic properties. The calculated total energy allowed us to investigate several structural properties in particular the lattice constant, bulk modulus, pressure derivative of bulk modulus and cohesive energy. A numerical first-principles calculation of the elastic constants was used to calculate C-11, C-12 and C-44. Band structure, density of states, band gap pressure coefficients, charge density and effective masses are also given. On the other hand, an accurate calculation of linear optical functions (refraction index and the dielectric function) is performed in the photon energy range up to 20eV. The results obtained are compared with other calculations and experimental measurements. (c) 2007 Elsevier B.V. All rights reserved.