عنوان مقاله [English]
In this paper, the electronic and optical properties of Na2S in orthorhombic structural phase have been investigated. Calculations have been performed by using wien2k package which is based on density functional theory and FP-LAPW method. From the calculated band structure, band gap is about 2.405eV. In valence band S atoms mostly contributed and in conduction band Na atoms.
The optical properties resulting are including the dielectric function, refractive index, extinction coefficient, absorption coefficient and Energy Loss function.According to the obtained results that indicate the maximum amount contribution imaginary dielectric function absorption and extinctions for energy absorption occurs and the maximum 5.5 eV and the maximum value of the real part dielectric function that indicates the maximum reflectance and energy refractive is observed near 5.4 eV. The results are good agreement with other available data.
 R.D. Eithiraj, G. Jaiganesh, G. Kalpana, M. Rajagopalan, First principle study of electronic structure and ground state properties of alkali metal sulfides Li2S, Na2S, K2S and Rb2S, physica status solidi 224 (2007) 1337-1346.
 G. Lindberg, A. Larsson, M. Reberg,R. Bostrom, R. Backman,A. Nordin, Determination ofthermodynamic properties of Na2S using solid state EMF measurement, The Journal of Chemical Thermodynamics 39 (2007) 44-48.
 A. Vegas, A. Grzenchnik, K. Syssen, I. Loa, M. Hanfland, M. Jansen, Reversible phase transition in Na2S under pressure a comparision with cation array in Na2SO4,ActaCrystallographica Section B 57 (2001) 151-156.
 P Blaha, Improved and updated Unix version of the original copyrighted WIEN-code, Computer Physics Communications 59 (1990) 339.
 H. Khachai, D. Rached, B. Soudini, FP-LAPW+LO calculation of electronic and optical properties of alkali metal sulfides under pressure, journal of physics condensed matter21 (2009) 095404.
 C. Kittel, Introduction to Solid State Physics, John Wiley & Sons, Inc, New York, (1996).
 S.W. Koch, Quantum theory of the optical and electronic properties of semiconductors, World Scientific Publishing Company Incorporated, (1994).
 A.M. Fox,M. Fox, Optical properties of solids,Oxford university press New York, (2001).
 K. Wakamura, Roles of phonon amplitude and low-energy optical phonons on superionic conduction, Physical Review B 56 (1997) 11593.