Journal of Alloys and Compounds 478 (2009) 297–302 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Review Elastic stability, electronic structure and optical properties of PtN 2 with pyrite and fluorite structures N. Bettahar a , S. Benalia a , D. Rached a,∗ , M. Ameri a , R. Khenata b , H. Baltache b , H. Rached a a Faculté des Sciences, Département de Physique, Université Djillali Liabes de Sidi Bel-Abbès 22000, Algeria b Laboratoire de Physique Quantique et de Modélisation Mathématique de la Matière (LPQ3M), Centre Universitaire de Mascara, Mascara 29000, Algeria article info Article history: Received 7 October 2008 Received in revised form 20 November 2008 Accepted 21 November 2008 Available online 6 December 2008 PACS: 71.15.Ap 71.20.Nr 71.15.Nc 78.20.Ci 62.20 Dc Keywords: Ground states Electronic properties Optical properties Elastic constants abstract We present the results of a theoretical study of the structural and optoelectronic properties of PtN 2 , using the full-potential linearized muffin-tin orbital method (FP-LMTO). In this approach, the local density approximation (LDA) is used for the exchange correlation potential. The calculated total energy allowed us to investigate several structural properties in particular the lattice constant, bulk modulus, pressure derivative of bulk modulus. The phase stability was determined from total energy calculations for both the pyrite (C2) and fluorite (C1) phases. A numerical first-principles calculation of the elastic constants was used to calculate C 11 , C 12 and C 44 . We estimated the Debye temperature of PtN 2 from the average sound velocity. Band structure, density of states, band gap pressure coefficients and effective masses are also given. On the other hand, an accurate calculation of linear optical functions (the dielectric function, refraction index and reflectivity R(ω)) is performed in the photon energy range up to 13.5eV. The results obtained are compared with other calculations and experimental measurements. © 2008 Elsevier B.V. All rights reserved. Contents 1. Introduction ......................................................................................................................................... 297 2. Computational methods ............................................................................................................................ 298 3. Results and discussions ............................................................................................................................. 298 3.1. The ground states ............................................................................................................................ 298 3.2. Elastic constants ............................................................................................................................. 299 3.3. Electronic properties ........................................................................................................................ 299 3.4. Optical properties ............................................................................................................................ 301 4. Conclusion ........................................................................................................................................... 302 References ........................................................................................................................................... 302 1. Introduction Metal and semi-conductor nitrides are an important class of materials having properties of fundamental interest as well as ∗ Corresponding author. Permanent address: Université Djillali Liabès, Faculté des Sciences, Département de Physique, Sidi- Bel- Abbés 22000, Algeria. Tel.: +213 48 54 43 44. E-mail address: rachdj@yahoo.fr (D. Rached). those used in a variety of applications [1–5]. Great theoretical and experimental efforts have been made to study the early transition metal nitrides [6–13]. Recently, the synthesis of platinum nitride [6], under high pressures and temperatures has stimulated further studies of noble metals nitrides [14–20]. Most recently, the exper- imental works contributed by Crowhurst et al. [16] reveal that the platinum nitride is of the pyrite structure and indicate that both zinc blende and fluorite structures are highly unstable at both ambient pressure and 50GPa. As well known, transition metal nitrides are usually metallic. However, the platinum nitrides with the structure 0925-8388/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2008.11.125