Ab initio calculation of the elastic properties and the lattice dynamics of the AgBr1-xClx alloy

作者：Bouamama Kh^*; Djemia P; Daoud K; Cherif S M

来源：Computational Materials Science, 2009, 47(2): 308-313.

DOI：10.1016/j.commatsci.2009.08.006

• Phonon
• Elastic constants
• AgBr
• AgCl
• Density-functional perturbation theory (DFPT)
• Virtual-crystal approximation (VCA)
• Supercell

The lattice dynamics and elastic properties of the ternary AgBr1-xClx alloy have been studied using first-principles calculations. These are done using the density-functional perturbation theory (DFPT) and employing the virtual-crystal approximation (VCA). We study the variation of the optical phonon frequencies (omega(TO) and omega(LO)) and of the acoustical phonon frequencies (omega(TA) and omega(LA)), the high-frequency dielectric coefficient (epsilon(infinity)), the dynamic effective charge (Z*) and the elastic constants (C-11, C-12, C-44) as a function of the composition (x). We find that the phonon frequencies as well as the elastic constants follow a quadratic law in x and agree well with the available experimental results. The elastic constant tensors for simple cubic 8-atom supercells with x = 0.25, 0.5 and 0.75 have been computed and are in good agreement with those obtained from VCA and experiments.

• 出版日期2009-12