First-principles study on the structural, elastic and electronic properties of platinum carbide

Abstract

First-principles calculations are carried out to investigate the structural, elastic and electronic properties of the newly synthesized noble metal carbide of platinum carbide (PtC). We use the plane-wave basis pseudo-potential method, in which both the local-density approximation (LDA) and the generalized gradient approximation (GGA) implanted in the CASTEP code are employed. The ground state properties such as lattice constant, elastic constants, bulk modulus and the final enthalpy of PtC in rock-salt (RS) and zinc-blende (ZB) structure are determined and compared with available experimental data. A series of geometry optimization was performed at a fixed value of applied hydrostatic pressure up to 120 GPa for the two different structures to simulate the experimental procedure of measuring the equation of state (EOS). From the pressure–volume data, we observed that the compressibility behavior of PtC in the RS structure is exactly with that of experiment. All the results reveal that the synthesized PtC would like to take the RS structure under high-pressure, which is meta-stable. The energy band structure and electron densities of states (DOS) of the two types of PtC are also presented. From the total and partial DOS, we find that the covalent bond of the RS structure is weaker than that of the ZB structure, which confirms that the former structure is meta-stable. Furthermore, both the DOS and energy band patterns show that the new compound is metallic.