The elastic constants and various optical properties of MnIn2S4 including the dielectric constant, absorption coefficient, electron energy loss function and reflectivity were calculated as a function of incident photon energy. Those results are discussed in this study and compared with available experimental results. | JOURNAL OF SCIENCE OF HNUE Mathematical and Physical Sci. 2014 Vol. 59 No. 7 pp. 135-143 This paper is available online at http ELECTRONIC STRUCTURE ELASTIC AND OPTICAL PROPERTIES OF MnIn2 S4 Nguyen Minh Thuy and Pham Van Hai Faculty of Physics Hanoi National University of Education Abstract. The electronic elastic and optical properties of MnIn2 S4 were investigated using first-principle calculations based on density functional theory DFT with the plane wave basis set as implemented in the CASTEP code. Our study revealed that MnIn2 S4 has indirect allowed transitions for both DFT and DFT U U 6 eV with energy band gaps of eV and eV respectively. The elastic constants and various optical properties of MnIn2 S4 including the dielectric constant absorption coefficient electron energy loss function and reflectivity were calculated as a function of incident photon energy. Those results are discussed in this study and compared with available experimental results. Keywords Inorganic compounds Ab initio calculations electronic structure. 1. Introduction Recently MnIn2 S4 which are ternary compounds of the AB2 X2 type have received much attention as materials which have potential for optoelectronic application and as magnetic semiconductors 1 . In the literature physical properties of MnIn2 S4 have been reported 1 2 . Recently the optical absorption spectra of MnIn2 S2 single crystals have been measured and it was found that the fundamental absorption edge is formed by direct allowed transitions 3 4 . However Bodnar et al. showed that MnIn2 S4 has both direct and indirect transitions 5 . Therefore further calculations of MnIn2 S4 are needed to clarify the origin of its band gap structure. Density functional theory DFT has been the dominant method used when making electronic structure calculations in solid state physics. In this work we report on the band structure optical and elastic properties of MnIn2 S4 using density functional theory. The .