Lattice dynamics and stability of CuInSe2

As a necessary step for envisaged ab initio studies of defects in CuInSe2 in a supercell approach, we performed optimization of lattice parameters and calculated F-TO phonons in a perfect crystal. Calculations have been done within the density functional theory, using norm-conserving pseudopotentials and basis set of atom-centered numerical functions (the SIESTA method). Lattice parameters yield good agreement with experimental measurements as well as with other recent calculations. The calculated phonon frequencies agree well with experimental values for the majority of modes but exhibit deviations in other cases, notably for modes where the scattering of experimental data is the largest, thus strongly indicating an anharmonic character of these modes. We demonstrate that the accuracy of the SIESTA method for the study of structure and lattice dynamics of CuInSe2 is not inferior to plane-wave approaches. (C) 2003 Elsevier B.V. All rights reserved.