Low compressible noble metal carbides with rocksalt structure: Ab initio total energy calculations of the elastic stability

The authors have systematically studied the mechanical stability of all noble metal carbides with a rocksalt structure by calculating their elastic constants within the density function theory scheme. It was found that only four carbides (RuC, PdC, AgC, and PtC) are mechanically stable. In particular, the authors have shown that RuC, PdC, and PtC have very high bulk modulus, which has been remarkably observed by the most recent experiment for the case of PtC. From the calculated density of states, it can be concluded that these compounds are metallic, like the conventional group IV and group V transition metal carbides.