First principles study of the electronic, elastic, infrared and electrical properties of LiZnPS4.

LiZnPS 4 is thought to be a promising mid-infrared optical crystal and lithium battery material, but its fundamental properties are still not well investigated. In this work, we performed a systematic study on its electronic, elastic, infrared and electrical properties. The results indicate that LiZnPS 4 is an indirect band gap crystal. Calculated partial density of states reveals that the top of its valence band is formed by the S 3p orbital while the component of the bottom of the conduction band is complex. The Zn 4p orbital is not empty in LiZnPS 4 owing to the tetrahedral coordination of the Zn atoms. Calculated elastic properties indicate that LiZnPS 4 is a mechanically stable crystal with elastic anisotropy. It has a relatively low Debye temperature of 294.8 K. Its infrared absorption spectrum was simulated and the origins of the strong peaks in it were revealed. Vibrational modes at the Brillouin zone center were illustrated and Born effective charges were calculated and discussed. Computed dielectric constants uncover that electrons contribute more to the total dielectric constants than ions. Studies imply that LiZnPS 4 –Li+ battery has a high theoretical voltage, a low electric capacity and a slightly high activation barrier. • Zn 4p orbital is found to be partly occupied for the special bonding pattern. • Infrared absorption spectrum is simulated and the related properties are studied. • Electrical properties of LiZnPS 4 are studied for possible use in lithium battery. [ABSTRACT FROM AUTHOR]