Materials Chemistry and Physics 111 (2008) 29–33 Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys The first principles study on PtC compound E. Deligoz a,∗ , Y.O. Ciftci b , P.T. Jochym c , K. Colakoglu b a Aksaray University, Department of Physics, 68100 Aksaray, Turkey b Gazi University, Department of Physics, Teknikokullar, 06500 Ankara, Turkey c Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland article info Article history: Received 19 August 2007 Received in revised form 28 January 2008 Accepted 13 February 2008 Keywords: PtC Band structure Elastic properties Thermodynamical properties abstract We have studied structural, thermodynamic, elastic, and electronic properties of platinum carbide (PtC) in zinc-blende and rock-salt structures by performing ab initio calculations within the LDA approxima- tions. Particularly, we have focused on the structural and the pressure dependence of elastic moduli and related quantities. The other basic key properties, such as the lattice constant, cohesive energy, the phase transition pressure, bulk modulus and its pressure derivative are also repeated and compared with the other available experimental and theoretical works. © 2008 Elsevier B.V. All rights reserved. 1. Introduction The transition metal carbides exhibit interesting physical prop- erties, such as high stiffness, high hardness and high melting point, which are important in many industrial applications. Although the physical and chemical properties of the transition metal carbides are, widely, studied in the past due to their technological impor- tance [1,2], there exist only a few theoretical works [3–6,8] on the structural, elastic, and electronic properties for other member of this class, platinum carbide (PtC). Ono et al. [7] recently synthesized the PtC at high pressure and high temperature using the diamond anvil cell technique. Ono et al. [7] predicted that the PtC is more stable in rock-salt (RS) structure according to their synchrotron X- ray diffraction data. Fan et al. [5,6] found that the RS structure is mechanically stable and the compressibility behaviour of RS-PtC is more comparable with that of experimental values. The same authors concluded that the RS structure is meta-stable and may transform to the more stable zinc-blende (ZB) structure under cer- tain conditions. Li et al. [4] and the present authors predicted that the ZB structure is the ground-state phase of PtC at zero pressure. A very recent paper by Peng et al. [8] which has appeared while revising this work also predicted that the ZB structure is more sta- ble phase for PtC. It is known that due to the large mass difference between Pt and C, the only X-ray diffraction analysis is not sufficient to distinguish ZB and RS structures [4,5] from each other. ∗ Corresponding author. Tel.: +90 312 2021233; fax: +90 312 2122279. E-mail address: edeligoz@yahoo.com (E. Deligoz). The main goal of this work is shedding light on the ground struc- ture of PtC and provides some additional information to the existing data on the structural, elastic, and thermodynamical properties of this compound by using the ab initio total energy calculations. The band-structural character, partial and total density of states, and the elastic moduli at high pressures are also estimated for PtC. The calculated properties varying with/and or without pressure are presented and compared with the previous works. The method of calculation is given in Section 2. The results and overall conclusion are presented and discussed in Sections 3 and 4, respectively. 2. Method of calculation The SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) code [9,10] was utilized in this study to calcu- late the energies and atomic forces. Siesta code solves the quantum mechanical equations for the electrons with the density functional approach in the local density approximation (LDA) parameterized by Ceperley and Alder [11] for the electronic exchange and cor- relation potential. The interactions between electrons and core ions are simulated with separable Troullier–Martins [12] norm- conserving pseudopotentials. The basis set is based on the finite range pseudoatomic orbitals (PAOs) of the Sankey–Niklewsky type [13], generalized to include multiple-zeta decays. We have gener- ated atomic pseudopotentials separately for both atoms, Pt and C by using the 6s 1 5d 9 and 2s 2 2p 2 atomic configurations, respectively. The cut-off radii for the present atomic pseudopotentials are taken as s: 2.13 p: 2.63 d: 2.67 f: 2.32a.u. for Pt, and 1.25a.u. for s, p, d and f channels for C. Relativistic effects are taken into account for Pt due to its heavy mass in the pseudopotential calculations. 0254-0584/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.matchemphys.2008.02.019