Eur. Phys. J. B (2016) 89: 90
https://doi.org/10.1140/epjb/e2016-60585-9

Regular Article

Structural stability and electronic properties of AgInS₂ under pressure

¹ National Institute for Theoretical Physics, Mandelstam Institute for Theoretical Physics, School of Physics, University of the Witwatersrand, Private Bag 3, 2050 Johannesburg, South Africa
² Computational and Theoretical Physics Group, Physics Department, Masinde Muliro University of Science and Technology, P.O Box 190-50100, Kakamega, Kenya

^a e-mail: donghomoise@gmail.com

Received: 20 July 2015
Received in final form: 14 November 2015
Published online: 6 April 2016

Abstract

We employ state-of-the-art ab initio density functional theory techniques to investigate the structural, dynamical, mechanical stability and electronic properties of the ternary AgInS₂ compounds under pressure. Using cohesive energy and enthalpy, we found that from the six potential phases explored, the chalcopyrite and the orthorhombic structures were very competitive as zero pressure phases. A pressure-induced phase transition occurs around 1.78 GPa from the low pressure chalcopyrite phase to a rhombohedral RH-AgInS₂ phase. The pressure phase transition around 1.78 GPa is accompanied by notable changes in the volume and bulk modulus. The calculations of the phonon dispersions and elastic constants at different pressures showed that the chalcopyrite and the orthorhombic structures remained stable at all the selected pressure (0, 1.78 and 2.5 GPa), where detailed calculations were performed, while the rhombohedral structure is only stable from the transition pressure 1.78 GPa. Pressure effect on the bandgap is minimal due to the small range of pressure considered in this study. The meta-GGA MBJ functional predicts bandgaps which are in good agreement with available experimental values.