Structural, electronic, vibration and elastic properties of the layered AgInP2S6 semiconducting crystal – DFT approach

Detailed first principles calculations of the structural, electronic and vibrational properties of the AgInP2S6 crystal are reported. The energy band spectra of the mentioned material using DFT/GGA-D methodology with the PBE functional was calculated for the first time. Stability of the AgInP2S6 crystals in contrast to Cu-containing representatives of M1M2P2X6 materials family (M1, M2 – metal, X – chalcogen) has been explained in the framework of the second-order Jahn–Teller effect. The high covalence of the Ag–[P2S6] bonds and strong hybridization of the 4d- and 5s-orbitals of the Ag atoms are responsible for the stability of the considered crystal. The calculated vibrational properties were compared with the available experimental data derived from Raman scattering spectroscopy and their good agreement was demonstrated. The electronic and vibration properties within the framework of a group theory approach were studied. Also elastic properties of the AgInP2S6 crystal were modeled and analyzed for the first time.